nell U ae 211. Ais” Ae, 1640 Me, Op CORNELL UNIVERSITY (Sl THE af lower Urterinary Library KC FOUNDED BY A [S ROSWELL P. FLOWER (902-1909 for the use of the N. Y. STATE VETERINARY COLLEGE 1897 Are Vessels Infected with Yellow Fever SOME: PERSONAL} OBSERVATIONS: - OTP E YT FOOD. ; ow ASHINGTON: * GovEREMENT PRINTING OREIOR. 1902. YELLOW FEVER INSTITUTE, BULLETIN No. 9. Treasury Department, Public Health and Marine-Hospital Service. WALTER WYMAN, Surgeon- General. Are Vessels Infected with Yellow Fever? SOME PERSONAL OBSERVATIONS. e By Surgeon H. BR, OARTER. SULT, 1902. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1902. YELLOW FEVER INSTITUTE, “Treasury Department, Public Health and Marine-Hospital Service, WALTER WYMAN, Surgeon-General. BULLETIN No. 9. Section (.—TRANSMISSION. J. H. WHITE, Asst. Surg. General, Chairman of Section. ARE VESSELS INFECTED WITH YELLOW FEVER ?—SOME PERSONAL OBSERVATIONS, By Surgeon H. R. CARTER. JULY, 1902. In a paper read before the American Public Health Association at Buffalo, September 18, 1901, Dr. Doty, the quarantine officer of New York, affirms the absence of secondary cases of yellow fever aboard ves- sels—i. e., that while cases of this disease contracted ashore develop aboard vessels, yet none are contracted aboard the vessel itself—that is, the vessel does not become ‘‘infected’’ with yellow fever. The experience of other quarantine officers has been different, and it may be of service then to group some cases already of record in which the contrary was observed. It is not proposed to collate a number of examples of vessels aboard which yellow fever was contracted, from the literature of the subject, but to give very briefly the history of some such vessels personally observed by the writer, from his own notes, during a four years’ service (1888 to 1891, inclusive) at the quarantine of the Gulf, Chandeleur and Ship islands. Here were received all ves- sels believed to be infected with yellow fever bound for all of the Gulf ports, except for New Orleans and from Tampa south. Consequently our clientele was considerable. The bulk of them, however, although certainly the worst class of vessels which entered the Gulf of Mexico, were not, in my opinion, ‘‘infected’’ when I received them—i. e., yel- low fever could not then have been contracted aboard them. I will premise here that I accept without reservation the conveyance of yellow fever by an infected mosquito of a certain kind, and that to 2 SEC. Cc. 7 Section C. 8 me a vessel ‘‘infected’’ with yellow fever is simply one which is har- boring these infected mosquitoes. Whether they came aboard already infected or, being aboard, became infected by feeding on cases of yellow fever developing aboard ship but contracted ashore, can in general be determined from the history of the spread of the infection. Indeed, it was primarily the history of these and other ships which led to the (tentative) formulating of the laws of the ‘‘interval between the infect- ing and secondary”’ cases of yellow fever and the ‘‘period of extrinsic incubation of places’? of that diease, which, and much else, are so clearly explained by the conveyance by a mosquito host. The deductions as to the disease being contracted aboard the vessels, when such deduction is made, are, however, independent of the assump- tion of any theory of conveyance. I do assume, however, that the period of incubation of yellow fever, rarely, if ever, exceeds six or six and one-half days. 1888.—SHIP ISLAND. I. Norwegian bark Magnolia, 946 tons, fifty-six days from Rio de Janeiro via Pensacola Bar, rock ballast. Left Rio de Janeiro May 20; left 2 men sick in hospital and had J aboard, considered yellow fever. Master sick third day out, May 22; died, May 27. All well till June1, then several (3) got sick at once. First mate sick, June 11; died, June 17; black vomit. All were sick on the way up except 2; 21 on crew list including the 2 men left in Rio de Janeiro. One of these who escaped fever had had yellow fever, and the other was a lad from Dantzig on his first deep-sea voyage. In all 17 men were sick of fever en route, of whom 5 died. The last case, Elias Eliasen, developed June 14. Here, save the captain, all sickened not less than eleven days after leaving Rio de Janeiro, and the first mate and Eliasen on the twenty- third and twenty-sixth day, respectively. They then contracted yellow fever aboard ship. The picture is that of an infection introduced aboard the vessel by the men who sickened in Rio de Janeiro—i. e., there were uninfected stegomyize aboard which were infected from these cases and conveyed yellow fever to the remainder of the crew, except the captain, who con- tracted it ashore. I did not.record the dates of the cases of the men left at Rio de Janeiro; it was shortly before clearing. The interval between an infecting and a secondary case is almost always fourteen days or over. II. Italian bark Riagino, Rio de Janeiro, for Pensacola, fifty-one days out ; rock ballast, 560 tons. No sickness in Rio de Janeiro until just before leaving, then sent 2 men to hospital. Left five days after. Log shows men were taken June 4 and June 6 and removed on June 6. Sailed on June 10. No one had been ashore save master and steward, using a harbor boat. First case reported sick en route June 21; 1 next day ; 6 sick en route; ‘ 9 Section C 3 deaths, June 28, June 29, and July 14, all with black vomit. Crew refused duty at second death. Last case well July 13. Sixteen on crew list; 2in Rio de Janeiro. Master had had yellow fever; steward sick just after leaving, not considered yellow fever. Six cases developed ten days after leaving Rio de Janeiro. Same remarks as were made of the Magnolia apply here. No record is made of where these 2 vessels lay in Rio de Janeiro, the writer not then appreciating the importance of this. 1889. My notes for 1889 are lost, and indeed there may have been in 1888 more than the 2 vessels given above, which should have been included in this paper; but my notes, taken at first solely with the view of determining the period of incubation of yellow fever, give data on only these two sufficiently definite to determine that they were infected— i. e., that yellow fever was contracted aboard. 1890. ITI. British ship Avon, in rock ballast ; 22 in crew, 4immune to yellow fever. Sailed from Rio de Janeiro April 20. All well in port and en route until thirty-eight days out, when a boy in port watch sickened with yellow fever. Taken to hospital, Gulf Quarantine, on third day, and died on sixth day. Another case developed two weeks later in a quarantine attendant who helped me clean up the room, sail locker, in which the boy was sick aboard ship. It is remarkable that there should have been only 1 case of yellow fever among the crew aboard this vessel. At the time it was ascribed to the fact that this boy, the only one on the port watch, helped a man, shipped in Rio de Janeiro and immune to yellow fever, overhaul his chest a few days before the boy was taken sick. Whether there was an infected mosquito in the chest which had survived this length of time, or whether there was any relation between the chest and the fever, may be a question. It in no wise affects the present question, that the dis- ease was, contracted aboard. It was the first case seen at this station that year. IV. British ship Curlew, from Rio de Janeiro, with rock ballast. No sickness was reported en route, in port, or on arrival. She was cleaned July 22 to July 23, 1890, and disinfection completed July 25, in the afternoon. One casé of yellow fever developod July 27, the sixty- fourth day out, in the early morning before day. V. British ship Chippewa, from Rio de Janeiro, with rock ballast. No sickness was reported in port, en route, or on arrival. She was cleaned July 26 and July 27, and disinfection completed July 28. One man, the quartermaster, developed yellow fever July 29, at night, sixty- eight days out from Rio de Janeiro. Section C. 10 The Avon made no port after leaving Rio de Janeiro and communi- cated with no vessel en route. The other 2 made no port save Pensa- cola Bar, and communicated with no vessel save the pilot boats there and off Mobile Bar. The infection in these.3 vessels, then, must have been contracted aboard. They lay in open roadstead at my station, 13 miles off shore and about } mile apart, and there was no visiting between them and none of their crews was ashore. ° VI. Spanish bark Castilla, fifteen days from Cienfuegos via Round Island Quarantine, in rock and earth ballast ; 14in crew. Hight days out from Cienfuegos to Round Island. All well in port, en route, and on arrival. Mate sickened fourth day after arrival at Round Island while discharging ballast. Vessel sent here in tow August 22. Mate had yellow fever; died on the sixth day of illness. Captain developed yellow fever day after mate’s death ; taken to hospital. No other cases of sickness aboard ; the remainder of the crew are, save 1, Manila men, and all probably immune to yellow fever, being mainly residents of Cuba for many years. Here 2 men developed yellow fever, 1 twelve and 1 seventeen days after leaving Cienfuegos. The infecting mosquitoes may well have been harbored in the hold, which the mate would probably not have visited until he anchored at Round Island and began discharging ballast, and in which the master would not be apt to go while the mate was on duty. VII. Spanish bark Grand Canaries, seven days out from Havana July 7. All well in port, en route, and on arrival and while in quar- antine. Crew probably all immune to yellow fever, being mainly Manila men and old residents of Havana. O. F., quarantine employe, went aboard as ballast master; next day developed yellow fever, July 11. This man had been exposed to no possible source of infection for the six months previous except this vessel. A case nearly similar to the above occurred in 1889, but I have no notes of it. VIII. Norwegian bark Queen of the Seas, in rock ballast, Rio de Janeiro for Pensacola, fifty-four days out. Left Rio de Janeiro with 17 men ; 6 deathsen route. All well in Rio de Janeiro. Lay at Mocanque, a healthful part of harbor. None save master allowed ashore, but’ he went in ship’s boat. Left 1 man at Rio de Janeiro—consumption. Shipped 1 man, a negro, in his place. Sailed April 23; master sick April 26; second nrate sick night of May 10; 2 men May 11; 1 man May 12;2 men morning of 13th; 2 during day of 13th; 1 man sick and 1 died 15th ; 1 man died 17th ; 2 sick 17th; 1 died 19th; 2 died 21st and 22d; 1 sick 21st; 1 died 25th; 183 sick en route, 5 died. The man shipped in Rio de Janeiro (negro) and 1 of the others immune by: pre- vious attack. The picture is very clear of a clean ship, infected by the illness of the master contracted ashore—i. e., had uninfected mosquitoes aboard, which became infected from the master sick of yellow fever, and conveyed it to the crew. 1 1 Section C. 1891. IX. British ship Curlew, fifty-seven days from Rio de Janeiro for Pen- sacola. Lay in the Gamboa last eight days. Two men sick February 27, taken to hospital that day ; sailed March 1. Master sick March 1; 5 men besides him that night. Two men March 4, 1 March 5, and 2 more during the day. Two men sick March 7. Two men died the 19th, sickening the 13th and 15th, respectively, both with black vomit. All aboard here, 19, were sick en route except 1, a Barbados negro; but don’t believe all had yellow fever, the crew having been badly fright- ened. The earlier cases and the 3 who died were undoubtedly yellow fever, as were the steward and mate. Here we have 2 cases, at least, developing thirteen and fifteen days after leaving Rio de Janeiro. _ X. Swedish ship Condoren, seventy-nine days out from Rio de Janeiro via Pernambuco for Mobile. Rock and earth ballast; 18 in crew. All well in port. Lay in Gamboa last five days. No shore leave allowed, but took ship’s boat to go ashore. Sailed March 3; 3 men sick March 5; 16 men sick, all told, up to March 26, and 6 deaths. Last man got sick March 26, when she put into Pernambuco short-handed and sent 3 sick men to hospital. Two men sick March 20; 4 men sick March 18; 1 man sick March 26 (really night of 25th). At Pernambuco she lay eleven days and was disinfected by sulphur. Shipped 8 new men, 4, probably 5, of them immune to yellow fever. Developed no sickness on the rest of the way up. Here 4 men developed yellow fever fifteen days from Rio de Janeiro. XI. German ship Gustav and Oscar, Rio de Janeiro for Pensacola. Lay at Cobras, a healthful place. One case yellow fever at Rio de Janeiro, March 22, sent to hospital March 24. No shore leave allowed. Sailed from Rio de Janeiro April 1; first case sickness April 7, 2 men ; 3 next day ; 1 next morning, and 2 during the day of the 9th. One death on the 10th, leaving 6 men sick. Captain sick on the 10th at night after supper. Lastcaseon14th. Two deaths on 11th ; 1 on 12th. Crew list shows 21 men left Rio de Janeiro; 14 sick and 4 deaths en route. It is reasonably certain that 4 of the remaining crew were immune to yellow fever by previous attack. XII. Norwegian bark Orown Prince, fifty-eight days out from Rio de Janeiro for Ship Island. Lay at Moncanque. No sickness aboard in Rio de Janeiro. No shore leave granted, and did not use ship’s boat to go ashore. Sailed April 29. Master sick second day out (April 30). Next case May 16; 3 (2 aft and 1 forward) became sick. May 17, 2 sick in morning, 1 in the day. May 18, 3 men in forecastle sick. May 20, 2 sick, 1death. May 21, 1 death, 1 sick. May 23, 2 deaths. May 24, 1 sick. May 28, 1 death last night. May 29, 1 sick this morning. M 0, 1 death. The 1 case on the 29th was the last case taken sick. There were 14 men aboard and every man had fever, 6 dying. She put into Barbados on June 10, disinfected and shipped (in quarantine) 4 Section C. al 9 new men, 1 probably unacclimated. No more sickness en route. All of these cases except the captain’s were not less than sixteen days from Rio de Janiero before developing. XIII. French ship Emily Postel, twelve days from Vera Cruz via Pensacola quarantine. Had ‘‘sickness’’ aboard just before leaving Vera Cruz, 1 man. Sailed from Vera Cruz July 28; no sickness since until crew went to discharge ballast, August 12. One man sick yellow fever August 15, 2 men the same, August 19, and 1 man August 20. Disinfection by sulphur was done on the appearance of the first case of yellow fever and no case occurred save the above. All were developed more than sixteen days after leaving Vera Cruz, hence from infection on board. The history points to infection (infected mosquitoes) in the hold. The picture given by the Curlew and Conderen are those of disease conveyed by mosquitoes coming aboard already infected just before they sailed. The infection was not introduced by the men who first sickened, the interval between them and the next cases was too short. Observe that they lay in the Gamboa, directly in the lee of a town badly infected. The other two give the usual history of a clean place (town or vessel) infected by some one developing yellow fever, con- tracted elsewhere, in it. XIV. Dr. G., assistant surgeon U. S. Marine-Hospital Service, developed yellow fever June 18 at the Gulf Quarantine Station, and died June 29. He wasimmediately from New York, where he had been on duty some months, and had been at the station but fourteen days when he was taken ill. There had been no case of yellow fever at the station that year. There were a number of vessels in quarantine, but the Gustav and Oscar (No. XI) was the only one I judged to be infected. On this vessel, as on the others, he had been with me inspecting, opening up drawers and boxes, and going into every compartment, etc., for the disinfection. I thought his infection was from this vessel. It was certainly from some vessel. I think it will be granted from the above that the ability of a vessel to carry the infection of yellow fever is no myth. Here are 13 vessels which did so carry ‘it collated from only three years’ observation at a single station. Such vessels are indeed rarer, much rarer, now than they were before 1894, yet they still come. Isaw 2 at Tortugas in 1894. Other cases are reported by Geddings and by Echemendia at the same place and at Port Tampa quarantine. Rosenau reports a case con- tracted aboard the steamship Vigilancia, from New York, plying between New York and Vera Cruz via Havana, in 1899. The steamship Bodo, last year (1900), from Bocas del Toro, for Mobile, developed 3 cases of yellow fever, seven, eight, and nine days out from Bocas del Toro. It would not be difficult, I think, to multiply instances of recent date. yet that they are rarer is without question. On the factors which have brought this about we can barely touch. 1 3 Section C. Obviously there are two methods by which vessels can become infected. (a) A case of yellow fever contracted elsewhere may develop aboard a vessel already harboring stegomyia mosquitoes which become contaminated from it. (6) The stegomyia mosquitoes may come aboard already contaminated. In the first case, there being nearly always over two weeks between the infecting and the first secondary cases of yellow fever, it results that, if the first case occurs after leaving port, vessels, even sailing vessels, from Cuba and the Caribbean Sea will generally reach quarantine and (if at a southern station) be disinfected—i. e., mosquitoes killed, before it is time for the secondary cases to develop, or, indeed, to be contracted. This agrees with all observation. In vessels infected in the second way, cases of yellow fever may occur after a very short or no interval from leaving port.. The causes, then, which have lessened the number of infected vessels at United States ports, are— 1. The very great falling off of vessels from Rio de Janeiro and Santos since the establishment of the Brazilian Republic. This does away with the bulk of the ‘‘long-trip vessels’? we used to have, which are the only ones developing secondary cases en route if infected by a case of yellow fever developing aboard. (Vide a.) 2. The replacing of sailing craft by steamships. That steamers con- vey yellow fever less frequently than sailing vessels has long been known. This is because they lie a much less time in an infected port, and the discipline of their crews is better ; no shore leave means no man goes ashore. They also make quicker trips, and thus are not apt to develop secondary cases en route, even if yellow fever contracted elsewhere develops aboard and they have the stegomyia aboard. Itis also to be noted that the worst parts of the harbors of Havana and Rio de Janeiro, above San Jose wharf and the Gamboa, have never been berths for steamships. Note, too, that the sailing vessels displaced are the foreign sailing vessels; the American schooner was less often infected than foreign vessels. 3. Especially since 1893, and to some extent before supervision had been kept by United States sanitary inspectors in the more dangerous yellow-fever ports over vessels bound for the United States, especially of passenger vessels. Certain anchorages have been recemmended as safe, others have been forbidden, notably the Gamboa at Rio de Janeiro and certain wharves and parts of the harbor at Havana. Passengers who it is believed will develop infection aboard have been barred ; ship- ment of new men in the infected port carefully supervised ; vessels in which yellow fever has occurred in port are disinfected before leaving, and many other measures taken to have the vessel leave port clean, or as nearly clean as commercial considerations allow. In general, the vessel owners, especially of the regular lines, have given hearty coopera- tion in these measures, as well as in keeping the crew aboard and in confining the visits of such officers as must go ashore to daylight. 3 SEC. C. Section C. 1 4 These restrictions, especially the last, have by no means been absolute for all classes of vessels, but are well observed, in Cuban and Mexican ports at least, by probably over five-sixths of the tonnage. The sani- tary measures to avoid infection (3) and the proportionate substitution of foreign sailing vessels by steamships (2) are without doubt the main factors acting in cooperation in lessening the infection of ships. No one can read Burgess’ list of infected vessels in Havana Harbor (Report, U.S. Marine-Hospital Service, 1896) without noting how great has been that decrease in recent years. We have said that if a case of yellow fever develops aboard a vessel harboring the stegomyia mosquito (proper conditions of temperature being premised) that they may become contaminated by feeding on him and infect others. A vessel which has no stegomyia aboard is like ‘‘noninfectible territory’? and will not communicate infection, even if cases of yellow fever develop aboard. I think it fair to say that ves- sels plying to and from southern ports of the United States will, during the summer season, generally have the stegomyia aboard, independently of its berth in tropical harbors, and may at times breed them in their water supply. This mosquito, however, seems to be rare north of Vir- ginia Beach (its distribution has not been sufficiently investigated, however), and a vessel plying to and from a northern port of the United States would not harbor this mosquito unless it came aboard in the tropical port. Now how far this mosquito goes or is borne from shore has not, I think, been directly investigated, but we do know that the crews of vessels moored off from shore (say 200 or more fathoms) in that part of Havana harbor seaward from the line between the Sta. Catalina warehouses and the Machina wharf do not develop yellow fever (unless close to some vessel which is infected). This means that contaminated stegomyia, at least, do not go so far from shore. Lying then at the anchorages accounted safe in Havana harbor, where the passenger vessels for the United States lie, one would think that the probability of any stegomyia coming aboard would be small. At Vera Cruz the vessels must lie nearer shore (although to windward of it), and experience shows that the crews of vessels lying there are not entirely safe, as I believe them to be in Havana, although infection in the part of the harbor picked out as safe is decidedly rare. The anchorages in both harbors regarded as safe are well to the windward of the town all sum- mer. A direct investigation of this matter—i. e., the presence of the stegomyia aboard vessels from northern ports in different parts of the harbor of Havana and other tropical harbors, should be made. To sum up— 1. Vessels aboard which yellow fever had been contracted—i. e., vessels infected with yellow fever have not been rare, at least at south- ern quarantine stations. 2. Such vessels are much rarer since 18938, and are not very common now. 1 5 Section C 3. That the diminution of the number of infected vessels reaching United States ports is due mainly to the sanitary measures for avoiding exposure to infection in the foreign port, and to the substitution of steam for sailing vessels. To some degree the falling off of the vessels from Brazilian ports is also a factor. 4, That a case of yellow fever developing aboard a vessel plying between southern ports of the United States and the tropics will prob- ably infect the vessel so that other cases can, if time be given, be con- tracted aboard her. 5. Such vessels, however, if short-trip vessels, not more than ten or twelve days en route after the occurrence of the case of yellow fever, will in general be disinfected at southern quarantine stations before any other cases have been contracted aboard, although harboring infected mosquitoes. 6. That a case of yellow fever so occurring aboard a vessel from a northern port of the United States would be able to infect her or not according to whether she had acquired the mosquitoes stegomyia fas. in the tropical port. 7. It is, in general, then necessary to disinfect all vessels running between southern ports of the United States aud tropical ports if a case of yellow fever occurs aboard, no matter where it be contracted ; while vessels running between northern ports and the tropics may, through precautions in tropical harbors, have no stegomyia aboard and are thus not infectable by cases of yellow fever occurring aboard. 8. Some vessels giving no history of yellow fever in port, en route, or on arrival—even when many days en route—are nevertheless infected and communicate the yellow fever to those who go aboard, vide Nos. IV, V, VI, VI. Note, also, the first case aboard the Avon, No. III, was thirty-eight days out from Rio de Janeiro. This is probably due to the infection (infected mosquitoes) in parts of the vessels unfrequented by the crew while en route, or to the crew being all immune to yellow fever. YELLOW FEVER INSTITUTE, BULLETIN No. 11. Treasury Dinars ‘Prabilig Health and Marine- - Hospital Service. ~ WALTER, WYMAN, Surgeon-General. SA RSSRTS AS CARRIERS OF - MOSQUITOES, BY Passed Asst. Surg. S. B. GRUBBS. MARCH, 1903. - WASHINGTON: : omnis PRINTING OFFICE. ‘o-0: 1908. a "site - YELLOW FEVER.- INSTITUTE. Treasury Department, Bureau of Public Health and Marine-Hospital Service. WALTER WYMAN, Surgeon-General. Buiuetin No. 11. Section C.—TRANSMISSION. Asst. Surg. Gen. J. H. WHITE, Chairman of Section. VESSELS AS CARRIERS OF MOSQUITOES. By 8. B. Gruss, Passed Assistant Surgeon, United States Public Health and Marine-Hospital Service. At the present time, when evidence is pointing with more and more clearness to the mosquito as the sole means of transmitting yellow fever, nothing is of greater interest to the quarantine officer than to decide to what extent and under what circumstances these infecting insects may be carried by vessels. This subject may be approached in three different ways: First, by observations on the length of time after leaving infected ports vessels may develop yellow fever; second, by experiments with mosquitoes under artificial conditions made to simulate as much as possible those of nature; and third, by actual observation of vessels arriving from ports at the time infected or where the presence of the Stegomyia fasciata render them liable to infection. While it will require data obtained by all these means and extend- ing over along period to arrive at any conclusions sufficiently accurate to allow them to influence quarantine procedure, still I believe the last method of observation cited will throw more light on the subject than ‘the first two, It is for this reason that every vessel arriving at Gulf Quarantine Station from Stegomyia-infected ports has, since the Ist of July last, been carefully examined to ascertain if mosquitoes were present on board, and,’ if present, their variety, where and when they came aboard, and under what conditions. Gulf Quarantine Station is an especially good point for these observations, from the fact that it is 10 miles from the mainland, and because vessels bound here do not pass near land, and so but rarely take on mosquitoes en route, and even these, as will be seen, are 26 26 always the marsh-bred varieties of Culex. Besides, the examination of at least a thousand mosquitoes on Ship Island has convinced me that there are no Steyomyza here. Each vessel inspected was carefully searched, the inspector being armed with a cyanide killing bottle, and in addition the captain was asked the following questions: 1. Were there any mosquitoes on board on your outward voyage, consisting of —— days? 2. If so, did they come aboard before departure from home port or at sea, and under what circumstances? 3. Were there any mosquitoes on board at your destination or on homeward voyage? 4. If in port— (a2) How far were you from shore? (b) Prevailing wind and weather? 5. If on homeward voyage (consisting of —— days)— (a) Were they from port? (b) Did they come aboard at sea, on what day, and how far were you from land ? (c) Were there wigglers in any of your tanks at any time? During the five months from June 1 to November 1 observations were made on 82 vessels, all arriving from ports where the Stegomyza is believed to exist in quantities. Of these 78 were sailing vessels and 4 were steamers. Of these 82 vessels 65 claimed to have had no mosquitoes aboard at any time during the voyage or at port of departure, and their absence having been confirmed by search, we can dismiss them from consider- ation and pass to the remaining 17. Five of these had mosquitoes on board at their ports of departure, 2 being rid of them as soon as they were well at sea, while 3 others carried’ them two days and were then no more troubled, except one schooner on which they reappeared in quantities five days before she reached this port, when she was 20 miles from shore. Nine sailing vessels, having no mosquitoes on board before sailing, had them appear at sea, in one case from the water casks in which the captain found larve. But in the other cases they doubtless came from land which was at the time distant—20 miles in one case, 15 miles in three-cases, 10 miles in one case, and 2 miles in the last two instances. . In all these vessels the mosquitoes found on board on arrival at this station were the common varieties of Culex, there being no Anopholes or Stegomyia among them. = 4 Stegomyia fasciata were found on board and were identified in the remaining three cases, as follows: . The schooner Susie B. Dantzler arrived from Vera Cruz, Mexico, on July 16, 1902, after a voyage of fifteen days. The captain stated 27 that mosquitoes came aboard in large.quantities at Vera Cruz, although he lay a half mile from shore and there were variable winds with squalls and rain all the time. The number of the insects decreased on the voyage but were always in evidence, and we caught four or five of them here. No larve were found in any of the tanks, and as the cap- tain had repeatedly examined them without result in his efforts to be rid of the mosquitoes, I believe the insects found on board here came all the way from Vera Cruz. The schooner Eleanor arrived from Vera Cruz on July 17, 1902, thirteen days out. She had no mosquitoes on board before reaching Vera Cruz, but there quantities came on board. Her moorings were half a mile from shore and the winds were variable. The captain stated that he could not get rid of the insects after sailing, although the number decreased very much and there were no larve in any of _the tanks. At the time of her inspection here we caught and identi- ’ fied a number of Stegomyta. The brigantine John H. Crandon arrived at the station J uly 27, 1902, twenty-two days from Vera Cruz, where she had one case ee yellow fever on board. At that port she lay a half mile from the sea wall, three-eighths of a mile from an infected prison, and within 200 yards of an infected vessel. Stegomyta fasctata were found on board by Acting Assistant Surgeon Hodgson before she sailed, as well as larve in the tanks. All during the trip there were mosquitoes in abundance, and a veritable plague of Stegomyia was found on board on her arrival here. There was a constant buzz in the forecastle, and anyone entering was sure to be attacked by several mosquitoes. Spec- imens were caught in almost every protected part of the vessel, and all were found to be the Stegomyta fasciata. The captain had emptied several water barrels because he found they were breeding mosqui- toes, but the water remaining had no live larve, although many old moults were seen. As breeding was surely going on in the tanks dur- ing a part of the voyage at least, it would be impossible to say how ‘long any particular mosquito had been aboard or if any of them had been brought here from the infected port. SUMMARY. The above facts may be summed up as follows: Vesssels having no mosquitoes on board at any time ...--.--..----------------- 65 Vessels having mosquitoes on board in port of departure ...-..----------------- 5 Vessels on which mosquitoes (Culex) appeared en route.......-..-------------- 9 Vessels arriving with Stegomyia fasciata on board......-.---------+-+-+-+-22--+ 3 Three and a half per cent, then, of all vessels brought Stegomyea on a voyage averaging Seventeen days. 28 CONCLUSIONS. From but one season’s observations ata single quarantine station we can not assume to draw any hard and fast conclusions regarding the probability of Stegomyia, infected or not, being carried by vessels. Nevertheless, I think we may conclude, first, that mosquitoes can come aboard vessels under favorable conditions when the vessel is not over 15 miles from shore; second, that Stegomyia can be carried from Mexican or West Indian ports to those of our Gulf States; third, that they can board a vessel lying at anchor a half mile or less from shore, being conveyed by the open lighters used or flying aboard, and finally, that a vessel moored a short distance from land may become infected with yellow fever, our old beliefs to the contrary notwithstanding. I wish to acknowledge the aid of Assistant Surgeons Burkhalter and Ebersole in collecting data and specimens. YELLOW FEVER IN STITUTE, BULLETIN Bo, 12. Treasury Department, ‘Public Health and. “Marine. - Hospital Services’ WALTER WMAM, Surgeon- -General. : / Tae Earty History op Quarannie: ORIGIN OF SANITARY MEASURES DERBY YELLOW FEVER, PED AGAINST Passed Asst. Surg. J. M. EAGER. — WASHINGTON: : GOVERNMENT PRINTING OFFICE. c 1903. YELLOW FEVER INSTITUTE, BULLETIN No. 12. Treasury Department, Public Health and Marine-Hospital Service. WALTER WYMAN, Surgeon-General. THe EARLY HISTORY OF (QUARANTINE: ORIGIN OF SANITARY MEASURES DIRECTED AGAINST YELLOW FEVER, BY Passed Asst. Surg. J. M. EAGER. MARCH, 1903. WASHINGTON: GOVERNMENT PRINTING OFFICE. 19038. YELLOW FEVER INSTITUTE. Treasury Department, Public Health and Marine-Hospital Service. WALTER WYMAN, Surgeon-General. . Buiuerin No. 12. Section D.—QUARANTINE AND TREATMENT. Asst. Surg. Gen. W. J. PETTUS, Chairman of Section. THE EARLY HISTORY OF QUARANTINE—ORIGIN OF SANITARY MEASURES DIRECTED AGAINST. YELLOW FEVER. : By P. A. Surg. 7 . M. Eacur. FHREBRUARY, 1903. The public sanitary measures included in the comprehensive term ‘“‘quarantine” have been more extensively applied in America against yellow fever than against any other disease. Most of these measures had their origin long before. yellow fever was known to the world. The way they came into existence and how they were later used as a protection against yellow fever is one of the most interesting topics in sanitary history—one without which no account of the prophylaxis of yellow fever would be complete. In the present writing the term ‘‘quarantine” is not limited to its narrower sense, but is taken to mean any restraint, owing to contagious disease, of intercourse on land or by sea. It includes such incidental measures as disinfection. The history of quarantine is closely interwoven with that of medi- cine in general and of shipping. We read of these practices being applied against leprosy in biblical times, and Captain Cook, the Eng- lish navigator, telis us that the savages of the South Sea Islands, who had not advanced beyond the stone age at the time of his visit to those islands, resorted to rude sanitary precautions in the case of arrivals from neighboring places. 3 4 The story of the beginnings of quarantine is associated particularly with the epidemiology of leprosy, pest, and syphilis. Cholera and yellow fever were later considerations. The first reported prevalence of yellow fever was at Bridgetown, Barbados, in 1647, the year before the great pest of Habana. At this time quarantine measures had been practiced against other malignant contagious diseases, a maritime quar- antine station having been in operation at Venice in 1403, nearly a century before the discovery of America. It was only necessary to include yellow fever in the category of contagious exotic diseases and apply against the malady the procedures already in vogue. The first appearance of yellow fever in Europe occurred at Lisbon in 1723, and is described in the article ‘‘ Yellow fever in Portugal” (Bulletin No. 4, Yellow Fever Institute, United States Public Health and Marine- Hospital Service). It was not, however, until 1821, following an extensive epidemic in Spain, that quarantine was applied in Europe against yellow fever. The Spanish academies were interpellated as to the nature of the disease, and as a result of their replies yellow fever was declared quarantinable. Inquiry in England in 1823 and 1824 was followed by an act of Parliament directing quarantine against yellow fever in the same way as against plague. Quarantine theory and practice have from the beginning followed medical dogma. Religion, astrology, and crude or false doctrines of etiology extended their influence. Like most branches of practical medicine, the practice of quarantine passed from the hands of priests into those of empiricists. It took ages for public sanitation to establish itself on a scientific basis. LEPROSY AND LAND QUARANTINES. The first quarantines of which any mention is made in literature were land quarantines used as a protection against leprosy. The ancients regarded this disease as of African origin, and Lucretius states positively that it first came from Egypt. In the Old Testament the first indications are found of precautions taken against contagious maladies. Leviticus, Numbers, and the First Book of Samuel give directions for the sequestration of lepers, first in the desert, then out- side the camp, and afterwards without the walls of Jerusalem. In these books the inspection of persons for the detection of leprosy is detailed. Persons afflicted with skin diseases were directed to present themselves before the priests. An observation of each case was made, and, according to minutely described symptoms, isolation of the patients was ordered for a prescribed period. The crusaders on their arrival outside the walls of Jerusalem found lazarettoes still in existence, and after taking the city from the Mussul- mans sent all contagious maladies to these isolated places. The name Hospital of St. Lazarus was given to the place of sequestration. Returning to Europe, the members of the military expeditions brought 5 back with them not only numerous diseases, but also the word “‘laza- retto,” as applied to a place for the isolation of the victims of com- municable maladies. As a result lazarettoes were built outside the gates of nearly all the principal cities of Europe. Leprosy itself had, however, been introduced into Europe many centuries earlier. It is spoken of as a foreign disease by the earlier Greek and Latin writers. Pliny thinks that leprosy was introduced into Europe by Pompey returning to Rome from. Syria after his celebrated triumph over fif- teen nations in Asia. It is implied that leprosy walked with the three hundred princes before the triumphal car of the conqueror. These surmises give rise to the interesting query whether leprosy was not the first quarantinable disease introduced by sea. As a quarantinable disease leprosy takes precedence in several ways. For instance, it was the first quarantinable disease (quarantinable from the point of view of the United States quarantine regulations) of which’ the causative germ was discovered. During the epoch of the crusades leprosy became widespread in Europe and resulted in the extensive establishment of isolation sta- tions. Leper houses existed at Metz, Verdun, and Maestricht as early as the seventh century, for long before the crusades the disease had spread from Italy into the Roman colonies of Gaul, Britain, and Spain, and thence into the most remote countries. Mathew Paris estimates that at the time of the great epidemic of leprosy in western Europe succeeding the movement against the Mohammedans 19,000 lazarettoes were in operation in Europe. Religious orders conducted the houses bearing the name of St. Lazarus, but in northern Europe many dedicated to St. George were under secular supervision. Not only were persons suffering from leprosy and other contagious dis- eases sent to such asylums, but the insane and individuals whose sep- aration from society was deemed an advantage to the populace or the ruling powers were also confined there. In these places of isolation quarantine measures, that afterwards had their application at maritime stations and ultimately were directed against yellow fever, developed primarily. Lepers were not strictly confined to the leper houses. They were, however, required to wear a special costume, to limit their walks to certain roads, to give warning of their approach by sounding a clapper, and to forbear communicating with healthy persons and drinking from or bathing in any running stream. PEST AND EARLY VIEWS OF ETIOLOGY. In connection with pest and later with syphilis the greatest advances of medizval times took place in public sanitary methods, leading to the establishment of maritime and land quarantines. During the Middle Ages more attention was given to the isolation of leprosy than of other diseases now known to be virulently contagious, for the reason 6 that the minds of medical men were hampered by accepted doctrines. . One of the first of these dogmas was founded on the fact that, while in the sacred Scriptures minute attention is given to precautions against leprosy and skin diseases, no measures are prescribed against pest. Yet most disastrous epidemics are recorded in the Old Testament. By the word pest is understood not only bubonic plague, but the different epidemic diseases, whatever they may have been, that were formerly included under that term. In their application to this group of maladies the various docrines of etiology had a most important bearing on etiology. The history is preserved in a great number of documents, many of them obscure and quaint, but all interesting as showing the gradual development of public sanitation. From an etiological standpoint the history of public hygiene in its relation to epidemiology is divided into four periods, during all of which widely diverse views of causation of epidemic disease were held, the state of knowledge in each successive epoch advancing nearer the truth. First came a chaotic period up to the time of Hippocrates, secondly the cen- turies that intervened from the time Hippocrates set forth his views of etiology to the middle of the sixteenth century, when Fracastoro, basing his observations on the epidemic prevalence of syphilis that extended throughout Europe, announced a theory of contagion. Then followed an interval lasting until the evidence of a living con- tagion gained credence. Lastly came the time when specific germs were found to be the cause of epidemic disease. The last era, how- ever, brings the history of quarantine to such a recent time as to be outside the scope of the present writing. The word plague aswell as pest was given by ancient medical writers to any epidemic disease that wrought an extensive destruction of life. Oalen, for example, used the word in this sense. History is replete with epidemics. Instances of ancient prevalences are the disastrous disease, recorded in II Kings, causing the destruction of the Assyrian army; the plague of Athens, described by Thucydides; the great pestilence in the reign of Marcus Aurelius, that extended over almost the whole of Europe, and the plague of Justinian, descriptions of which are given by Procopius and Evagrius. The plague of Justinian lasted for fifty years and has a decided interest in connection with the present subject, having been introduced in all probability largely by sea. It began at Pelusium,in Egypt, 542 A. D. After spreading through Egypt it appeared the next year at Constantinople. In sub- sequent years it advanced over the entire Roman world, making its initial appearance in seaboard towns and radiating inland. Frequent epidemics occurred in succeeding centuries, one of the most important of which was the great cycle of epidemics in the fourteenth century, which has been given the name of the ‘“‘ black death.” Throughoutall 7 this extensive period notions and practices relating to public sanita- tion were being evolved in accordance with the prevalent tenets of causation. In the earliest period religion, superstition, and stellar influence took the principal place in the confused ideas of etiology. Ill-ordered doctrines led to all sorts of irrational practices. Among the Greeks, in the rites of Msculapius, the sick were not permitted to enter the temples, where they underwent treatment, without first being purified by various baths, frictions, and fumigations. All this was accompanied by ceremonies similar to those practised within the temples, namely, magical performances and fervent prayers recited in a loud voice, often with musical accompaniment. As an accessory to - the purification preliminary to being admitted, the patient was required to pass the night stretched on the skin of a sheep that had been offered as a sacrifice. Here he was-ordered to compose his mind for sleep and await the arrival of the physician. Throughout these ages as well as in more recent times a fanciful association between the phenomena of the material world and the destinies of mankind closely linked the doctrine of etiology with astrology. The persistent belief of learned men in the relation of stellar conditions to epidemics is in part explained by the fact that astrologers who predicted epi- demics wrought charms against the impending pestilence, thus saving their credit, in event the disaster did not materialize, by claiming that it had been averted through their efforts. These primitive views of the origin of epidemics did not necessarily place the cause of the dis- ease outside the earth and its immediate surroundings. Winds, thunder and lightning, fogs, and other meteors were blamed for caus- ing pestilence, and the flight of birds and insects were supposed to be dependent phenomena. -Xanaphanes, five hundred or six hundred years before Christ, expounded an idea that the sun was a torch and the stars candles that were put out from time to time. According to his notion, which was seriously accepted, the stars were not heavenly bodies in the wider sense, but meteors thrown off from the earth. So a belief in stellar influence did not carry the mind outside worldly ranges. For this reason other practices than prayers and sacrifices were believed to be effective. They consisted chiefly in efforts to dis- sipate the meteors, such as huge and numerous fires, and to avoid meteoric influence by confinement in closed or otherwise protected places. During the period under consideration, the promptings of supersti- tion were paramount and the epidemiologists of the times confined themselves principally to interpreting the signs of the heavens. More advanced views came as the result of reasoning, but the path of dis- covery by experimental science was not entered upon until after many centuries. ETIOLOGY ACCORDING TO HIPPOCRATES. The doctrines of etiology took a more determinate form under the teachings of Hippocrates. According to Hippocrates, disease has its origin either in the régime of life or in the air that surrounds the living body and enters into it. He made therefore a twofold etiolog- ical division of diseases, those dependent on the personal régime, and those dependent on the quality of the air. Regarding the latter class, when many individuals are attacked by the same disease at the same time, he supposed the cause to be a common one, namely, the air breathed. Hippocrates believed that a régime of life, which differs with different persons, could not be the cause of a malady that attacks alike the young, the old, men and women. On the other hand, when diseases of different sorts occur, it was clear to him that the cause is individual. Epidemic disease, according to the Father of Medicine, is often promoted by a specific, unknown, and extraordinary condition of the air due to the presence of the guid divinwm, which may also exist in miasms and certain other impure things. This guzd divinum has given much trouble to the followers and commentators of Hippoc- rates, and the judgment as to what he conceived it to be must be left to the fancy of the student of his writings. It seems probable, how- ever, that Hippocrates meant the scourge of divine wrath. It was this very idea that for centuries prevented the application of sanitary measures to epidemic disease. Men regarded pestilence as a punish- ment inflicted by the Almighty on delinquent humanity and an attempt to turn aside a weapon borne in the divine hand was considered vain and impious. The influence of Hippocrates’s views, with their bearing on sanita- tion, extended with slight abatement almost to the time when Fracas- toro announced his doctrine of contagion. Throughout all this period, moreover, the controlling power of Platonism held experimental inquiry in check. It was believed that the true nature of things could be discovered by the action of reason and not in any important degree by experience and observation. Thus, it will be seen, the measures directed against epidemic disease were often misguided, ineffective, and dependent on all sorts of false doctrines. GALEN’S VIEWS OF EPIDEMIOLOGY. Galen, not dissenting from the views of Hippocrates, was of the opinion that any disease that caused the almost simultaneous death of a large number of people should be regarded as of the nature of pest. He did not hold to any view of contagion in these maladies, that is, of their direct communication of man to man, though he evidently believed that the corruption of the air was more intense in the neigh- borhood of the sick than elsewhere. Pest, he declared, was born of a 9 pollution of the atmosphere and assailed man by way of respiration. This doctrine was ‘accepted by the pupils of Galen. In the commen- taries of the books of Hippocrates on epidemics, or popular diseases, as they were called, it is asserted that pestilential maladies proceed from a special condition of the heavens. These commentaries, at one time attributed to Galen, have since been demonstrated to be the production of his disciples. The long line of Greek, Latin, and Arabic medical writers down to the time of Avicenna, the Moham- medan physician, adhered to the teaching of Hippocrates and Galen, and when they speak of contagion the term must always be under- stood to mean contracting a disease by breathing altered air. The masters of medicine of the middle ages held similar opinions. Ber- nardo Gorgonio, professor of medicine at Montpellier, France, in 1300, and Arnaldo da Villanova, who lived toward the end of the twelfth century, gave the name of pestilent fever to every deadly fever and maintained the cause to be a corruption of the air. Gug- lielmo Varignara, professor of medicine at Bologna in 1302, not only denied the contagious nature of measles and smallpox but declared that the buboes of plague were not contagious. Gentile, who died of pest at Foligno, Italy, in 1348, believed that the poison of pest existed in the air and was due toa putrefaction of this medium. John Godes- den, a leading English physician of the fourteenth century, announced the same views. De Chauliac, an eminent French physician of Avig- non, who observed the terrible epidemic of 1348-1361, recorded casually his idea that pest could be contracted by contact with the sick, but assigned as a primary cause decomposition of the air due to the con- junction of planets whereby a certain subtle substance is evolved capable of producing epidemics. Another famous physician of those times, Raimondo da Vinario, who was a spectator of the epidemics of pest in 1348-1361 and 1373, says that it is a very dangerous thing to have to do with persons stricken with pest; that one person sick with pest may infect an entire city; that those employed in public hygiene in times of epidemic prevalence take the malady by contagion; that phy- sicians more than any other class are likely to catch the disease; and that monks are generally exempt from pest because they are isolated in monasteries and thus free from outside exposure. Still there is not room to believe that this master of medicine had any precise concep- tion of the nature of contagion. Like so many others, he put his faith in corruption of the air brought about by an influx of stars, planets, and constellations, and in poisonous exhalations emanating from the earth. The danger of contact with the sick he conceived to be due.to the air filled with pestilential poison that had been inspired and afterwards exhaled by the victims of the disease. Da Vinario held also that garments worn by the sick and other fabrics in close contact with them contained the infective principle, and hence should ° 10 be transported with the sick to a distant and isolated place. Notwith- standing all this, he does not mention the necessity for purification of infected things nor ever suggest the caution of destroying fomites. There can be no stronger evidence than this of the tenacity with which the physicians of the middle ages adhered to the accepted doctrines of their predecessors. THE BEGINNINGS OF RATIONAL ETIOLOGY. 1t took centuries of involuntary observation to shake the idea that epidemics are of celestial origin and to be combated by prayers, fast- ing, and processions. The first advances toward broader ideas were not made by medical men. The record of reformed views is found in works.on jurisprudence and in the narratives of travelers. In the books of jurisprudence of the emperors of the East it is noticed that care should be exercised in having relations with persons arriving from places where pest reigns. It was ordered, in consequence, that those so exposed should be separated from others for the purpose of observation. The term of forty days (whence the word quarantine) is named, this being the supposed maximum period of the duration of acute maladies. Whether this isolation was practiced in a particu- larly selected piace or in the houses of the suspects is not known. Merchants traveling in the East and detained at Alexandria or Cairo during the prevalence of pest observed that cloistered monks did not contract the disease. Many of these merchants, exiled by pestilence, staid constantly within the boundaries of their residences, transacting all business through barred windows and from terraces that crowned the house tops. The stubbornness with which medical men held to the doctrine of aerial corruption of celestial origin is shown by the report made to the Marseille government in 1720 by a body of dis- tinguished physicians, in which the condition of the air was pronounced to be the sole cause of pest, the idea of communicability from man to man being absolutely rejected. One of the most ancient edicts commanding the segregation of suf- ferers from pestilential maladies had for its authors two laymen, Sagacioand Pietro de Gazata, and is found in the chronicles of Reggio d@Emilia. The document, dated 1374 and written in low Latin, orders that all persons sick with pest be taken outside the city, into the open country, a camp, or the woods, there to remain until dead or cured. The parish priests are required to promptly report all cases of pest under pain of death by fire. After registering these historical facts, the chronicler adds: And I saw in this same year that these orders were observed in Reggio, for which cause all were grieved and terrified more than by the fear of the illness which, when God permits, can not be averted. 11 ORIGIN OF THE DOCTRINE OF CONTAGION. The credit of having created the doctrine that pest is contagious by contact with the sick and their effects is chiefly due to Jacobo della Torre, known also by the name of Jacopo da Forli, from the ‘name of a city ca central Italy, where he was born in the geennd half of the fourteenth century. Contagion had been referred to obscurely and timidly from Aristotle down, but now the idea took a practical form. The old notion was that fomites were a sort of tinder that caught from the air an infection existing independently of the sick. Many writers, including Galen, believed there was an extreme degree of atmospheric pollution in the vicinity of the sick, rendering such neighborhoods dangerous, but this was considered a primary cause of the illness rather than a direct emanation from the sick. Della Torre’s doctrines were not accepted by the various schools of medicine and were for a time absolutely forgotten. Fracastoro pro- claimed the same theories at a later period, when they were better received, and to him is generally given the honor of announcing the theory of contagion. Jacobo della Torre advised the magistrates of his native town to remove outside the city all persons affected with pest and to isolate them, as well as all persons who had-been with them. The authorities were warned against delay, for it was avowed that every precaution would be futile should the disease become dif- fuse throughout.the city. In his recommendations no mention is made of purification, but he asserted his disagreement from the accepted belief in the stellar origin of the infective principle. Della Torre’s disciple, Michele Savonarola, attained greater eminence than his mas- ter, and so far vindicated the honor of his school as to declare that even persons in good health may transport the pestilential virus to distant places, and that those who are not brought in association with the vic- tims of pest or with pest-bearing things escape the disease. But Savonarola did not fully indorse the teachings of his preceptor. He could not shake off a belief in astrology and admitted that the origin of pest resided in a disorder of the air generated in consequence of planetary contact. Giovanni da Concorrezzo, toward the second half.of the fourteenth century, was so profoundly convinced that pest came exclusively from universal aerial pollution that he denounced as useless every precaution to check the advances of the disease and affirmed that all measures designed to avert contagion are inefficacious. At this period, when the world had about decided that in epidemics sanitation was not worth while, three observing men lent their influ- ence to broader views and thus gave a potent stimulus to the doctrine of contagion. These writers were Alessandro Benedetti, Marsilio Ficino, and-Gerolamo Fracastoro. 12 BENEDETTI AND FICINO. Alessandro Benedetti, anatomist and military surgeon, wrote a treatise on pest, published in the last decade of the fifteenth century, in which is presented a résumé of his doctrine concerning pest. Pest, he declared, is not only catching by contact with the sick, but by fomites. The latter, he believed, are capable of receiving and pre- serving the contagion for long periods. Convalescents from pest, and the things that have been in relation with them, should, he said, be purified before being brought in touch with healthy persons. Marsilio Ficino was born in Florence in 1483, and passed his child- hood in the court of Cosmo de’ Medici. He was a priest as well as a physician. Pest had, in Ficino’s time, tormented Tuscany, and in 1479 broke out in Florence. The Grand Duke Cosmo de’ Medici requested Ficino to prepare a book treating of the pest with the scope of instructing the people how to protect themselves from the scourge. The book, published about 1480, was written in Italian. In writing it, Ficino was associated with Tommaso del Garbo, Mengo da Faenza, and others, and the volume bore the title of Counsel Regarding the Pest. The book is a rare one in its original tongue, but fortunately was translated into Latin and is still preserved in different libraries. The list of the works of Ficino refers to this treatise by the title of Antidotus, and it isso cited in many medical books printed in later years. The theories given in this work as to the origin and nature of epidemic disease are the same fantastic stuff that antecedent writers dealt out, but the ideas as to how the disease may be imparted are of a much better sort. The view is advanced that pest can be communi- cated from man to swine, and that cats and dogs convey the disease. The reader is informed that pestilential poison may abide in the air for long periods and may infect food. Advice is given to boil all drinking water, or to impregnate it with iron rust; to dilute wine with water so prepared; to add an acid sauce to the food; to choose dry food and fruit grown in balsamic and elevated regions, and to dwell on hills or in the mountains. Treating of prophylaxis and die- tetics during times of pest, there is a long list of injunctions relative to exercises of the body and the quality of the food. For example, it is enjoined to shun the heat of the sun and of tires; to avoid sweating and the drying of sweat on the body; not to eat fish, or if needs be, to eat small fish from some clear running stream with a rocky bed, and to fry them in oil and treat them liberally with lemon juice, pep- per, and cinnamon; and, lastly, there is an enumeration of fruit and vegetables to be chosen or avoided. Overeating and overdrinking are admonished, and it is advised to cook all meat well and prepare it with aromatic condiments. To preserve the health of those in attendance 18 on the sick, it is directed to keep as far apart as may be from the bed- side; to ventilate the sick rooms; to fumigate the house with burning terebinth wood; to carry in the hand a firebrand, a pot of lighted charcoal, or a sprig of rue, mint, sage, or myrtle; and to bathe the body, morning and evening, with warm vinegar. Directions are given to sprinkle the house with preparations of terebinth, juniper, sandal, rose, rosemary, laurel, and similar herbs. The reader is informed that walls, partitions, and all structures made of wood are capable of preserving the contagion for more than a year, and that their disease-bearing qualities should be corrected by washing, fumi- gations, and fire; that garments of wool and similar stuffs, if not exposed to the air and sun, fumigated often, and well washed, may still contain contagion after three years. The statement is made that the morbid principle can diffuse itself through division walls and enter neighboring habitations. Caution is prescribed in moving ani- mals, money, furniture, and bundles from place to place because of the danger of conveying disease. FRACASTORO AND SYPHILIS. Gerolamo Fracastoro is generally credited with being the author of the theory of contagion, but, as has been seen from a review of the works of previous writers, it can only be claimed for him that he elaborated the theory, presented it in a popular form, and lent to the idea the influence of his high authority. An important event at this period of history was the extensive prev- alence of syphilis in Europe, a spread of the disease that gave it every likeness to a general pestilence. The chroniclers of this occur- rence were convinced that the disease could propagate itself at a dis- tance, and that it could be communicated by intercourse not more inti- mate than conversation and social commingling. The malady diffused itself through all classes of society, and history names a king and other potentates among the victims. In Italy the belief prevailed that the disease had gained access to the country with the invading army of Charles VIII, of France. The Italians called it the ‘“‘morbo Gallico.” In France it took the name of the Neapolitan disease. Wide credence was gained by another theory to the effect that the malady had come in by sea with the naked savages of America. In this case it must have spread and taken root very speedily, for it is said that when Columbus went to Barcelona on his way to pay homage to Ferdinand and Isabella, of Spain, syphilis flourished in that seaport; public prayers were being offered as in times of pest, and precautions were being taken against the disease as in case of leprosy. Laws were made in France for the regulation of syphilis. By an act of the Senate at Paris, dated March 6, 1496, persons affected with 14 the disease were forbidden under pain of the halter to have any deal- ings with well persons, and it was ordered that the sick should be seg- regated in places set aside for their reception in the Faubourg St. Germain. Notwithstanding the rigor of the ordinance, many stricken persons eluded the vigilance of the sanitary guards and moved about in the city of Paris, thereby spreading the disease. The provost then found it necessary to make public cry, warning all persons that there- after pretensions of ignorance would be disregarded by the authori- ties, and any individual, native or stranger, afflicted with syphilis and found witbin the city would be summarily cast into the river and left to his fate. Some years later there was similar trouble in the Italian part of the Tyrol, trouble which so interfered with one of the most important ecclesiastical gatherings of the times that Pope Paul III, by advice of Fracastoro, removed the Council of Trent to Bologna. Fracastoro had previously written a dignified and graceful medical poem, in Latin, entitled ‘‘Syphilidis sive Morbus Gallicus,” after whose hero, the shepherd Syphilus, the disease received its name. His interest in this prevalence of syphilis influenced Fracastoro to publish, in 1546, the work ‘‘De Contagionibus.” The great feature of this writing is the presentation of the subject in such a catching way that it took hold on the popular mind, and even had decided effect in loosening the deep-rooted medical opinion of the times. The lesson of contagion was taught by a number of clever similes. For example, Fracastoro divides contagious diseases into three classes, namely, dis- ease catching by contact, in which he compares the mode of com- municability to the way in which one decayed fruit spoils another perfect one; disease carried by fomites, a process likened to the per- sistence of soot on a smoky wall; and disease conveyed to a distance, in which manner the virus is carried just as the volatile essence of garlic or of an onion is borne through space, affecting the nostrils and causing the eyes to water. Fracastoro taught that the poison of dis- ease consists in corpuscles, and that it affects first the minute particles of the animal body. He says that this poison persists in the body, ia fomites, or in the air, in proportion to a kind of stickiness existing between the conveying medium and the poisonous corpuscles; and that woolen fabrics and the like absorb, retain, and transport con- tagion with ease, because they contain interspaces to lodge the cor- puscles, and are of a nature to protect the poison from the light, heat, cold, air, dampness, and other conditions injurious to it. So we see that, with the acceptance of the views of Della Torre, Benedetti, Ficino, and Fracastoro, things were fairly in the way for a beginning of quarantine on a practical basis. 15 MARITIME QUARANTINE. Maritime quarantine originated in connection with the Levantine trade. Its early history is associated with that of shipping in the Mediterranean, especially with that of the traffic of Venice, Genoa, and Marseille. Although commercial activity in these waters was initiated by the Pheenicians, the maritime pioneers, records of disease introduced by sea are not found bearing earlier date than the period when Roman navigation was well established. As has been seen, the practice of isolation was first applied against communicable disease by the Hebrews, but their lazarettoes, it appears, were little used in con- nection with foreign trade, leaving out of the question commerce by sea. In the exchange of commodities with foreign countries the Hebrews were largely dependent on the Phenicians and Arabs. Had the Jews been active in outside commerce, we should probably read in the Old Testament of sanitaiy laws applicable to caravans and vessels. As has been already mentioned, Pliny implies that leprosy was introduced into Europe by Pompey on his triumphal return from the _ East. It is altogether probable that the Roman ships, laden with spoil from Syria, and bringing many prisoners of war to Italy, carried in leprosy. In connection with the question of the first recorded introduction of disease by sea a curious error has entered into writings on the subject. J. Freind, adducing evidence in his History of Medicine that Procopius was a physician, quotes a translation of Procopius’s works by Dr. Howel, and says that the great Byzantine historian describes the pest at Constantinople (A. D. 534) as having originated at Pelusium, in Egypt. This is indeed what Procopius wrote. But it happens that later writers—evidently reading Freind’s history—say that Procopius states the epidemic in question was carried to Constantinople by ships and that this invasion of disease became later the foundation of the quarantine establishments on the Mediterranean coast. It is, how- ever, true that the Italian epidemics of the sixth century began in the maritime towns and thence spread inland; but it does not follow that the writers of the time considered the intervention of ships essential to the introduction of disease by sea. For example, Francesco Alfano, professor of medicine at the University of Salerno, which in those days was reputed to be the greatest medical school in the world, writing in 1577, says that the corrupt air capable of introducing pest may be blown over sea and land for long distances; otherwise how could it be explained, he asks, that pest was transported from Ethiopia to Athens and to all Attica?’ It was considered, moreover, that a ship might easily be pestridden. Even by going to sea a vessel with all well aboard at the time of departure could not always escape the 16 scourge. The infection extended over the water. Matteo Villani, of Florence, writing in 1581 of the epidemic of 1346, which spread from Asia into Turkey, Egypt, Russia, Greece, and Italy, says that in those evil days numbers of Italian galleys flying from the pest left the stricken ports for healthier harbors. Their crews perished miserably at sea. Some reached Sicily, Pisa, and Genoa, and the disease went with them. EARLY MARITIME SANITARY LAWS. ’ There is but little known of ancient laws relating to maritime com- merce, and even this little was lost to the world until 1147. The story isan interesting one. Justinian, during his reign, confided to ten juris- consults the task of collecting and adjusting the numerous Roman laws, together with the various sentences and rulings of judges and magis- trates. A compendium of these documents and of the laws promul- gated during the rule of Justinian was published. It is known by the name of the Codex of Justinian. The only part of this code that treats of ships is called the Digestwm, and it was lost for hundreds of years. Finally, in 1147, the papers were discovered at Amalfi and made public. The Digestwm treats of the reciprocal rights of the owners and renters of ships, but no mention is made of sanitary mat- ters. During the long period when this important legal instrument was lost, the Venetians, Genoese, and other Latin maritime nations supplied the deficiency in part from the initial sources of Roman law and in part by custom and agreement. Of this sort are two collec- tions, one known by the name of Recognoverunt Proceres and the other called the Consolato del Mare. Besides these, there is a great number of documents, such as constitutions, decrees, ordinances, sentences, and the like, which pertain to maritime rights. It is a remarkable fact that, notwithstanding the detailed attention given to most maxims relating to shipping, the Lecognoverunt and the Consolato del Mare are silent too on the subject of sanitation. Therefore, in the Middle Ages, in event of contagious prevalences, it rested with each individual city or country to make such provisions as were deemed opportune. Such an edict is the one, said to be the most ancient of its kind, already mentioned as having originated at Reggio d’Emelia, in 1374, and com- manding notification and segregation of cases of plague. The Venetians were, it is generally admitted, the first to make pro- vision for maritime sanitation. As far back as the year 1000 there were overseers of public health, but at first the office was not a per- manent one. The incumbents were appointed to serve during the prevalence of an epidemic only. The first information we have of this kind of public office is under date of 1348, when Nicolaus Venerio, Marinus Querino, and Paulus Belegno (their Christian names given in the Latin of the text) were appointed overseers of public health. 17 These officers were authorized to spend public money for the purpose of isolating infected ships, goods, and persons at an island of the lagoon. A medical man was stationed with the sick. As a later result of these arrangements, the first thoroughly constituted maritime quarantine station of which there is historical record was established in 1403 on the island of Santa Maria di Nazareth, at Venice. The island had pre- viously belonged to the hermit monks of the order of St. Agostino. The record of the foundation of the first maritime quarantine is found in a Venetian manuscript written by Giovanni Tiepolo, a patrician. The chronicle reads: 1403. The pest began at Venice. M. J. ROSENAU, “Passup ASSISTANT: ‘iraeaea: ‘= HERMAN B. PARKER, Passep Assistant SURGEON, EDWARD FRANCIS, Assisranr SURGEON. © o . GEORGE E. BEYER, Acrine ASsIgTANT SURGEON. MAY, 1904. ™~ WASHINGTON: | “GovERNARENT PRINTING ‘OFFICE. ye 1905. ee YELLOW FEVER INSTITUTE, BULLETIN No. 14. Treasury Department, U. S. Public Health and Marine-Hospital Service. WALTER WYMAN, Surgeon-General. REPORT OF hee WORKING PARTY NO. 2, YELLOW FEVER INSTITUTE. EXPERIMENTAL STUDIES IN YELLOW FEVER AND MALARIA AT VERA CRUZ, MEXICO. BY M. J. ROSENAU, Passep Assistant SURGEON. HERMAN B. PARKER, Passep Assistant SURGEON, EDWARD FRANCIS, Assistant SURGEON. GEORGE E. BEYER, Active Assistant SURGEON, MAY, 1904. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1905. CONTENTS. eface and acknowledgments -____..____.----- 222-2222 ee ene e eee eee \e cause of yellow fever....._:......-----.---.-- doetereurstay nays meee se Resulting from mosquito bites (Table 1).._._..__...-.-2--.--- 22-2 -- ne Resulting from blood inoculations (Table 2)__........-.-..----------- ie filtration of yellow fever blood._._...___.__..---. 2-2-2 e222 ee ee eee Yellow fever produced by the bites of mosquitoes _...__....-...._--.-- Yellow fever produced by the inoculation of blood serum ___.________- marks on filtration experiments with yellow fever blood..........--._-. sting of filters with objects of ‘‘ ultramicroscopic ”’ size -_._.._...-_----- .e filtration of certain virtises_.____...-.---.----------------2--- eee eee MITES! 6 ose topos ee eee eae a eaeeee as eae eee eee cess .e filtration of malarial blood___ .__--._...-----------------------+-----. Estivo-autumnal fever -.-__-.-_.----- Be ae Spa ala de ner ose tats Longevity 3:5 25.8 seen sere icee es ee ee eee tee, OVIPOSITING oo 55 sah sisc2 Bec a az kdemaeece eg e5a ae Gere eet cece Size" OL SCFCONING 2. adc bs ose atest osce ahowisnea tessa cas seemganiiedeses sinf6CtiONn. 6XPeTIMCNts = a..co scence semeccdamasaessen dene sesesmeccianseeeee mmary and conclusions--_..-...-------.---------------------- eee LIST OF ILLUSTRATIONS. Phate 1. Wild yeasts in pure culture.__.__...-..- 2-22-22 ee ee eee eetaeeee 2. Character of the malarial parasites in the blood of Filomena Mar- tinez at the time it was filtered __.-.....-...------------------ 3. Character of the malarial parasites in the blood of Andres Mendez at the time it was filtered...-.....-...-...------------- ---+--- FiaurE 1. Rosenau’s spreader for making blood smears --__-.-.-.---------- : 2. The arrangement used for filtering through a Pasteur-Chamber- laid DOUBIEZB 2 accgces set sc oacescceeer sree seeemee hice scene 8. Showing the method of filtering through a Berkefeld filter by means of a hand vacuum pump .----- --.--------------------- 4, Showing screen containing 16 strands or 15 meshes to the inch. Allows male and female stegomyia fasciata to pass. -.-------- 5. Showing screen containing 20 strands or 19 meshes to the inch, through which stegomyia fasciata can not pass -----------.-- TEMPERATURE CHARTS OF— Mar COS O00 2 tripe jaians reer pene ete ype el pernape ted German Ramos... ..--._.-._--- = Bot ee Oe a acess asi lal aden Pagt Guadalupe Gomez ----....222 00 ee ee eee eee Filomena Martinez _._.__.._ 222-2222 eee eee eee eee Wndres Mendez. 2iescn demons asc a mined a ee eaaebotodeion HAS POLED OF isi Sais ciocis erence cn tar eects tee aes ONOIOI CINE: A = sure oehcmmnmecdae acter y tne eine cine a emi einciaaiatateies 83 96 PREFACE AND ACKNOWLEDGMENTS. Working Party No. 2, Yellow Fever Institute, consisting of Passed sst. Surg. Herman B. Parker, Asst. Surg. Edward Francis and Act- z Asst. Surg. George E. Beyer, was detailed by the Surgeon- meral U. S. Public Health and Marine-Hospital Service, with the iproval of the Secretary of the Treasury, to Vera Cruz, Mexico, oril 27, 1903, for the purpose of making further studies upon the use and methods of transmission of yellow fever. Doctor Parker returned to Washington upon official business June 1903, and on September 13, 1903, returned to Vera Cruz with Passed sst. Surg. M. J. Rosenau, Director of the Hygienic Laboratory, who d in the meantime been appointed chairman of the commission, th instructions to repeat that part of the work of Working Party 9. 1 relating to the Mywxococcidium stegomyie. Professor Beyer left for New Orleans on October 4 to resume his tties at the Tulane University of Louisiana. The remaining three members of the working party continued work Vera Cruz until November 28, 1903, when, on account of the sub- lence of the yellow fever epidemic and scarcity of material, they turned to Washington. : The commission made a brief report to the Surgeon-General, signed r all of its members and published in the Public Health Reports r January 15, 1904, as follows: ndings of Working Party No. 1, Yellow Fever Institute, not all corroborated by Working Party No. 2. WASHINGTON, December 18, 1903." IRGEON-GENERAL. Sir: We have the honor to report that, as a result of our studies at Vera uz, Mexico, this summer, we have not been able to corroborate all the findings Working Party No. 1, Yellow Fever Institute, Public Health and Marine- yspital Service, having found phases of the organism described by them as yeococcidium stegomyie in normal mosquitoes. Respectfully, M. J. Rosenav, Chairman Working Party No. 2. H. B. Parker, EXpwarpD FRANCIS, Gro. E. BEYER. The commission was now, January 18, 1904, dissolved, and its embers permitted to publish individually any further matter bear- g on the summer’s work. This bulletin, therefore, has been prepared by two members of the mmission, Doctors Rosenau and Francis, who have continued cer- in phases of the work, but who here wish to make full acknowledg- (v) VI meht of the services rendered by their colleagues. Especial mention should be made of the fact that the mosquitoes which fed on yellow- fever cases and subsequently were used to produce the initial case of experimental yellow fever (Marcos Cruz) were handled by Professor Beyer. Credit is also due to Professor Beyer for the scheme of experi- mentation which was partly carried out. This plan was published by him in full in the New Orleans Medical and Surgical Journal for May, 1904, entitled “The mouth parts and salivary glands, normal and otherwise, of the yellow-fever mosquito.” Professor Beyer was a member of Working Party No. 2 from May 5, 1903, to January 18, 1904, and-was in charge of the laboratory at Vera Cruz from June 8 to September 17, 1903, during the absence of Doctor Parker. Asst. Surg. Joseph Goldberger was associated with us throughout the entire summer, having been detailed to Vera Cruz to supervise the sanitation of vessels leaving for the United States. He helped us find suitable cases of yellow fever and malaria in the hospitals from which he infected a large collection of mosquitoes, and he also made many of the observations which we have embodied under “ Miscellaneous observations on mosquitoes.” The plans of the commission were laid before Governor Dehesa, of the State of Vera Cruz, who was always most zealous in furthering the scientific investigation of yellow fever, and offered us many facilities. To Mr. Alexander M. Gaw, of Jalapa, Mexico, we desire to express our particular appreciation of many thoughtful kindnesses and mate- rial assistance. To Dr. Eduardo Licéaga, president of the superior board of health of Mexico, and to his representatives in Vera Cruz, Doctors del Rio, Iglesias, and Garcia, we wish to express our thanks for their interest in the work and for many courtesies, thoughtful kindnesses, and mate- rial assistance, The United States consul, Mr. W. W. Canada, and Acting Asst. Surg. S. H. Hodgson, U. S. Public Health and Marine-Hospital Serv- ice, were always ready to assist us in every way possible. . Finally, we wish to express our appreciation to the Surgeon-Gen- eral of the Public Health and Marine-Hospital Service for his con- tinued interest and support which made the work possible. M. J. Rosenav, ; Passed Assistant Surgeon, Chairman. : Herman B. Parker, _ Passed Assistant Surgeon. ©. Epwarp Francis, dl Assistant Surgeon. Gro. E. Bryer, Acting Assistant Surgeon. YELLOW FEVER INSTITUTE. Treasury Department, Bureau of Public Health and Marine-Hospital Service. WALTER WYMAN, Surgeon-General. BULLETIN No. 14. Section B.— ETIOLOGY. P, A. Surg. M. J. ROSENAU, Chairman of Section, EXPERIMENTAL STUDIES IN YELLOW FEVER AND MALARIA. By M. J. Rosenau, Passed Assistant, Surgeon, Herman B. Parker, Passed Assistant Surgeon, Epwarp Francis, Assistant Surgeon, GEoRGE E. Bryer, Acting Assistant Surgeon. THE CAUSE OF YELLOW FEVER. The cause of yellow fever is not known, but we have to consider the. Myxococcidium stegomyiw of Parker, Beyer, and Pothier. These authors described in some detail the life cycle of a supposed animal parasite in infected mosquitoes closely resembling coccidia. It was our first duty to investigate the merits of this announcement. We therefore first sectioned about one hundred normal mosqui- toes, Stegomyia and Culex, both male and female. A study of these slides soon convinced us that bodies resembling Myaococcidium stego- myiae may be found in normal mosquitoes and that for the most part these bodies were yeast cells in various stages of reproduction. Car- roll had called our attention to this in a conversation and subsequently discussed it in an article published in the Journal of the American Medical Association for November 28, 1903. Since then the French commission, working at Rio de Janeiro,? has come to the same conclusion. « Marchoux, Salimbeni, and Simond: La fiévre jaune; rapport de la mission francaise. Ann. de Inst. Pasteur, tome XVII, November, 1903. (49) EXPLANATION OF PLATE 1. Wild yeasts in pure culture isolated from banana at Vera Cruz, Mexico, in the summer of 1903. Stained with hematoxylin and eosin. All the specimens show deeply stained granules. 1. Shows the lemon-shaped budding forms of Saccharomyces apiculatus. 2 and 4. Other budding forms. 38. Well marked granules. 5. Ovoid forms with granules. 6. Filamentous yeast. J Plate 1. WILD YEAST IN PURE CULTURE ISOLATED FROM BANANA AT VERA CRUZ, MEXICO, IN THE SUMMER OF 1903. STAINED WITH HEMATOXYLIN AND EOSIN. ALL THE SPECIMENS SHOW DEEPLY STAINED GRANULES. 51 shaudinn®? considers yeasts as normal commensals of all mosquitoes believes they play an important part in the physiology of the ct, generating the gas that is almost always found in the eso- zeal diverticulum and also producing an enzyme or other irritat- substance which, when injected under the skin of man, causes the immation resulting from mosquito bites. Schaudinn considers e yeast cells to play a very important part in the economy of the ct and believes them to be hereditarily passed from the adult ugh the egg to the larve and pupe. osquitoes fed upon fruits have many more yeast cells in their es than those fed upon blood or other material. This we were to confirm. We also fed mosquitoes upon pure cultures of | yeasts growing upon banana, and found that the insects fed on 1 a fermenting diet would soon be so swelled up with gas that r bodies looked like transparent air bubbles. Insects so fed do t badly and it is difficult to keep them alive over a week in trop- temperatures. ome of these wild yeasts are very interesting; one in particular— Saccharomyces apiculatus, which is found widely spread through- nature especially on fruit. This particular yeast assumes at times racteristic spindle or lemon shapes, with a bud at the pointed , somewhat resembling one of the conjugating forms of protozoan inisms with which it has been confused. 7e were enabled to isolate this yeast in pure culture from the anas at Vera Cruz only after some difficulty. The ordinary plate hods failed because the other saccharoniyces overgrew the small nies of S. apiculatus. The following expedient finally succeeded: overripe and fermenting piece of banana containing the mor- logic forms desired is planted into orange juice. This culture ium was made by simply squeezing the. oranges, taking care not et any of the oil of the peel, then filtering until clear, and steriliz- by heat in test tubes. As the Saccharomyces apiculatus is a bot- yeast, the growth which appears ¢ at the bottom of the test tube in lve to eighteen hours is examined under the microscope and, if the ser forms are found, transferred to another tube containing Ze juice. This is repeated until a number of subcultures are le, and as the Saccharomyces apiculatus grows better in the orange e than the other yeasts, the latter are quickly left behind until ire culture is obtained. Te have noted in stained preparations of these wild yeasts that + sometimes show red chromatin (?) granules in a blue protoplasm schaudinn, Fritz 1904, Generations- und W: irtswechsel bei Trypanosoma und ochaete (vorliufige Mitteilung.). Arb. a. d. k. eee Berl., 4°. 13046—05 m——2 52 when stained with polychrome methylene blue, such as Goldhorn’s. We call atention to this, for isolated yeast bodies of this character stained thus might lead to errors of interpretation. THE BLOOD IN YELLOW FEVER. We are fully justified in concluding that in the blood of yellow- fever cases there is a living entity floating free in the plasma and capable of reproducing the ‘disease. The positive results obtained in the filtration and inoculation experiments done by Reed and Carroll, corroborated by the French commission and ourselves, is sufficient proof of that statement. We carefully examined many blood smears stained with poly- chrome methylene blue of Wright and Goldhorn, and failed to see the presence of any body which could be considered to stand in any causal relation to the disease. The smears were taken from 17 cases at periods of five hours to six days after the onset of the disease. In every case blood was taken within the first three days of sickness. In several cases the blood was taken daily or on alternate days. The corpuscles and plasma were carefully searched. The red cells often showed minute blue bodies, usually round and sometimes slightly irregular, which resemble those ascribed to cell degeneration or nuclear rests in anemia. The mononuclear leucocytes and polymorphonuclear neutrophiles often showed in their protoplasm small, round, clear spaces having a punched-out appearance. These spaces could not be made to take up any one of several stains employed. They were also found in mala- rial and normal blood. In making our blood preparations we used a method devised by one of us (Rosenau) about four years ago, which has been in constant use in the Hygienic Laboratory since, and as it has proven so satisfactory in our hands we will describe it. The technique was suggested by the glass slides commonly used for this purpese. The instrument consists of a little glass apparatus we call the “spreader,” made by simply welding two pieces of solid glass rods together, as shown in fig. 1. The short arm should be true, so as to lie flat when applied to the slide, and should be severai millimeters shorter than the width of the slide. A drop of blood is taken from the ear or finger tip and placed upon one end of the slide in the usual manner. The spreader is then applied to the drop, and if the glass is clean the blood will at once be drawn by capillary attraction across its whole length; it is then spread by a gentle, even stroke, without undue pressure, along the 53 le. Very beautiful préparations, with the corpuscles lying singly, : thus obtained. Chis little apparatus can readily be made at the blowpipe. Fia. 1.—Rosenau’s spreader for making blood smears. THE PERIOD OF INCUBATION OF YELLOW FEVER. [he exact period of the incubation of yellow fever is a matter of vat importance in quarantine and public-health work. For years ; quarantine regulations of the Marine-Hospital Service required letention of five days, which was considered amply safe to cover : period of incubation of the disease. The regulations of the Pub- Health and Marine-Hospital Service, promulgated August 10, )8, lengthened the time of observation in special cases to six days, sing this action upon the recent experimental work which has made sossible to determine the period of incubation of yellow fever with at exactness. 54 We have collected from the literature all the cases in which the period of incubation may be stated with precision. These are of course for the most part experimental cases in which the exact time of the mosquito bite is known, and in which the onset of the disease has been carefully observed. The disease usually begins sharply with a chill, pains, and rise of temperature. In such cases the precise hour of onset may be stated, | but sometimes the attack begins vaguely or at night. Then the period of incubation can be stated only approximately. In the following table the onset of the disease is considered from the time the temper- ature rises, thus omitting the prodromal symptoms of lassitude, headache, etc, which sometimes send a patient to bed twenty-four hours before the fever sets in. Of course from a practical standpoint in public health work only those cases infected in a “natural” way—that is, by the bites of mosquitoes, can be considered. -Subjoined is a table of 40 such cases. TaBLE 1.—Period of incubation in yellow fever, resulting from bites of infected mosquitoes. [Carter: ‘‘The period of incubation of yellow fever,” Med. Rec., Mar. 9, 1901: also, private cor- respondence. Observations of the disease following one short exposure in the infected region at Orwood, Miss., during the epidemic of 1898.] Case No.— Bitten. ~ Attack. Incubation. In these observations, which were of a clinical nature, no attempt : was made to determine the period of incubation within hours, any- thing less than one-fourth of a day being disregarded. [Reed, Carroll, Agramonte, and Lazear: ‘The etiology of yellow fever; a preliminary note,” Phila. Med. Journ., Oct. 27, 1900.] Case No.— Bitten. Attack. Incubation. i 6 |) eee Aug. 27,2 p.m_-__... Aug. 31 (?) a.m... 3 days 17-22 hours (about). 14 (11) --------- Aug. 31, lla. m-_.___. Sept. 6 (?) p. m._....- 6 etrn (about). According to the . authors, 6 days 2 hours. 55 TaBLe 1.—Period of incubation in yellow fever, etc.—Continued. sed, Carroll, and Agramonte: ‘ The etiology of yellow fever; an additional note,” Journ. Am. Med. Assoc.,.Feb. 16, 1901.] 4 ‘ 2 Jase No.— Bitten. Attack. Incubation. (pce Joncas Dec. 5,2 p.m-_......- Dec. 8, 11.30 p. m 3 days 93 hours. (B)euseteseces Dec. 8,4 p.m _..._.-. Dec. 14,9a,m__.._-.. 4 days 20 hours, took to bed; 5 days . 17 hours, onset of fever. Dec. 12, 9.80 p.m. __._ 3 days.11 hours (about). Dec. 15, noon... -| 3 days 194 hours (bed). t Dec. 25, noon. _...__.- 2 days 19} hours since shortest, and times—Dec. 21, 4 days since Jongest exposure. noon, and Dec. 22, 4.30 p.m. (6) .--..-----] Dec. 30, 11 a.m ......| Jan. 3, 10.30 a. m_....| 8 days 22} hours. [Reed: ‘‘ Experimental yellow fever,” Am. Med., July 6, 1901.] Jase No.— Bitten. Attack. Incubation. Jan. 19, 3.30 p.m -.... 3 days 23} hours. Jan. 31, 9.30 a. m-_ 3 days 2} hours. -| Jan.6, ll a.m _- 3 days 6 hours. Jan.7, 2p.m-___.__... 2 days 22 hours. eed and Carroll: “Etiology of yellow fever; a supplemental note,” Am. Med., Feb. 22, 1902.] Jase No.— Bitten. Attack. Incubation. (css ee ws Sept. 16, 4p. m__.....| Sept.19, 4.30 p. m_....| days 4 hour. (2) eocusmence Oct.9, 4p. m-_....---- Oct. 13, midnight ....| 3 days 8 hours (about). [Guitéras: Revista de Med. Trop., vol. 2, No. 10, 1900-1901.] Case No.— |° Bitten. Attack. Incubation. . 23, 26, (?) p.m--.--- 3 days 10 hours (about). . 8, 12, (?) p. m..--- 4 days 5 hours. . 8, 11, (?) p. m----- 3 days 3 hours. 9, 14, (?) &, m ._--- 5 days 3 hours. 13 1%, % .45p.m..| 3 days 19 hours. 14 18, (?)6a.m ....| 3 days 21 hours. 14. 20, forenoon.-...| 5 days 21 hours (about). . 22. 25, (?) 4.30p. m-_.| 3 days. arker, Beyer, and Pothier: “‘A study of the etiology of yellow fever,” Yellow Fever Institute, Bull. No. 13, March, 1903.] : Case No.— Bitten. Attack. Incubation. Sept. 4, 9.30 a.m -.--- Sept. 7, (2) a. m.-...- 3 days 2 hours (about). hi Salimbeni, and Simond: ‘La fievre jaune,” Rapport de la Mission Francaise, Institut pean ; Pasteur,. Annales, November, 1903.] Yase No. — Bitten. Attack. Incubation. 83 days 18 hours. 3 days 22 hours. 5 days 22 hours. 7 days 5 hours. " i i by infected mosquitoes patient had received injections of blood from ae Da adios immunity: B cc. blood twelve days old; followed fifteen days later ity eight days old. 3 eae baal been given 20cc.serum taken on the eighth day and passed through a rkefeld filter; six days later 20 cc. of same serum not filtered ; subsequently bitten by infected »squitoes. The serum injections may have induced a partial immunity, which delayed the set and modified the disease, for he had a mild attack. 56 TaBLy 1.—Period of incubation in yellow fever, etc.—Continued. [Francis and Beyer.] Case No, — Bitten. Attack. Incubation. AO Sr vacpceprerse eters Sept. 11, 9a. m.,and | Sept. 14, 3.30 p. m_...| 3 days 7 hours, or 2 days 1 hour. Seat. 12, 2.30 p. m. ei A study of the 40 cases in this table discloses the fact that yellow fever usually begins about three days after the mosquito bites. The period of incubation resulting from this natural method of conveying the disease is rarely under three days. We have but one such authentic instance, namely, two days twenty-four hours (case No. 24). The longest period observed was seven days five hours, but it must be noted that the man who had this unusually long period of incubation had previously been treated with injections of immunizing sera, which may have delayed the onset and modified the disease, for he had a mild attack. Leaving this case (No. 39) out of consideration, the longest period of incubation resulting from the bites of mosquitoes is the case (No. 14) of Reed. Carroll, Argamonte, and Lazear, in which an incubation period of six days two hours was observed. This corresponds strik- ingly to Carter’s clinical observations in which he reports a case with an incubation period of five and three-fourths days. See case No. 12 in Table 1. The French, commission, working in Rio de Janeiro, came to the concluson that the period of incubation of the disease may be much longer than this; but we find on analyzing their work that they drew their inferences largely from the disease produced by such artificial means as the inoculation of modified blood serum. One of the conclusions of this commission was that yellow fever may not infrequently incubate for twelve days before symptoms declare themselves. They state that “this incubation of twelve days is not absolutely rare. We have had occasion to see that the natural infection may also present an incubation equally léng.” With this statement we must take issue, for the long experience of the Public Health and Marine-Hospital Service in the many wars it has waged against yellow fever has amply demonstrated that for practical purposes five days is sufficient to cover the period of incubation of the great majority of cases. An analysis of all the cases reported in Table 1 supports this view. / The French Commission reports several cases in support of their contention. One, a young man 18 years old, who took yellow fever ten days after having arrived in Petropolis from Rio de Janeiro. Petropolis is a village free from yellow fever. Another instance 57 was a girl 12 years old, who was taken with yellow fever ten days after returning from Rio, her father having sent her to Petropolis because his wife and three other children had the fever. We do not doubt that Petropolis is “ indemne,” free of Stegomyia fasciata, and that the disease has never been known to spread there; but the communication with Rio is close, and if yellow fever cases are brought to’ Petropolis it is conceivable that infected mosquitoes may also be carried. There are many other “loopholes” which weaken observations of this kind, and we have therefore refrained from placing them in our table. The last case cited by the French commission is as follows: On board the vessel Messageries, returning to Hurope, having taken passengers from Rio de Janeiro, an isolated case of yellow fever declared itself among the latter passengers between Dakar and Lisbonne; that is, nine to fourteen days. It was our experience that some cases of yellow fever are so mild that they are detected with difficulty, especially under such unfavor- able conditions as on board ship: ‘“ The isolated case” on board the Messageries may have been the second case, especially as the fourteen days is sufficient to cover the “ extrinsic incubation ” of the. disease. The literature has several instances of such cases. They should be carefully considered before drawing definite conclusions. It is interesting to compare the period of incubation resulting from exposure to infection in the “ natural” way with the period of incuba- tion resulting from experimental yellow fever, produced by the inocu- lation of blood or blood serum. The following table shows 17 such cases: TABLE 2.—Period. of incubation in ygom Sever, resulting from the injection of ood. (Reed, Carroll, and Agramonte: ‘‘ Experimental yellow fever,” Am. Med., July 6, 1901.] Case No.— Inoculated. Attack. Incubation. Jan. 4, lla,m-__..-..- Jan. 8,9a.m-_-.....- 3 days 22 hours. Jan. 8,9 a.m___ -| Jan. 11,9a.m_-. -| 2 days 12 hours. Jan. 22,1 p.m-__--....- Jan. 24,9a@,m-__...._. 1 day 19 hours. Jan. 25, 12.45 p. m-.,-.| Jan. 28, 1.15 p. m._... 3 days 1 hour. No. 1 received subcutaneously 2 cc. blood taken on second day. No. 2 received subcutaneously 1.5 cc. blood taken 12 hours after beginning of attack. No. 3 received subcutaneously 0.5 cc. blool taken on second day. : No. 4 received subcutaneously 1 cc. blood taken 274 hours after commencement of disease. [Reed and Carroll; ‘The etiology of yellow fever; a supplemental note,” Am. Med., Feb. 22, 1902.] Case No.— Inoculated. Attack. Incubation. WB) cowensconce Oct. 15, 4p. m__------ Oct. 20, 6 p.m. .weoee 5 days 2 hours. Case 5 received subcutaneously 0.75 cc. partially defibrinated blood 15} hours old. 58 Taste 2.—Period of incubation in yellow fever, etc.—Continued. {Reed and Carroll: ‘The etiology of yellow fever; a supplemental note,” Am. Med.,Feb. 22, 1902.] Case No.— Inoculated. : Attack. Incubation. GAD) ate nace cic cere Oct. 15, lla.m-..-.-- Oct. 19, 3p. m-_ 4 days 4 hours. it {% epee een Oct. 15, 11.05 a, m....| Oct. 19, noon... . -| 4 days 1 hour, Cases 6 and 7 were inoculated subcutaneously with 3 cc. of an equal volume of water and serum filtered through a Berkefeld filter. (Marchoux, Salimbeni, and Simond: “La fievre jaune,” Rapport de la mission frangaise, Insti- tute Pasteur, Annales, November, 1903.] Case No.— . Incubation. BiG) ie ncceceaeew DCG BOTW a4 onc dies ov earswiecd oon asians aeaacuaennnsaceeictindsace ns 5 days 5 hours. 9 5 caEseeeawn 5 cc. serum heated to55° for ten minutes; five days later, 10cc. | 12 days 12 hours. heated to 55° for ten minutes; seven days later, 1 cc. blood. This was a ‘‘remarkably benign case,” and as the man had been injected previously with heated yellow fever serum. the immunity produced probably explains the long perio: of incubation as well as the mildness of the attack. MO 4 )iccinsiscse/e 5 cc. serum heated to 55° for twenty minutes; seven days | § days 5 hours. later, 10 cc. serum heated to 55° for ten minutes; eight days later, 1 cc. serum heated to 55° for five minutes. Then 1 cc. serum. . The same explanation for this unusually long period of incu- bation as above, especially as a parallel case similarly treated showed an immunity. lec. serum filtered through a chambeciand F filter_. 5 days 18 hours. 12 (8) . pir OO ncavvcadesopnrs 12 days 18 hours. 0.1 ec. (1 aren} of si 4 days 18 hours. 5 ce, blood, 5 days Olda. Centrbl. ftir bakt., Abt. 2. bd. 5. 1899. p. 27. ¢ Deut. med. wochenschr., bd. 28, 1902, p. $92. 73 of 16 generations in fowls; it resisted 60° C. for three hours, and after one hour in a vacuum tube at 100° C. it was virulent. Hydrophobia.—Remlinger and Riffat-Bey « ground up a rabbit’s brain in water together with a bouillon culture of chicken cholera and filtered it by aspiration through a Berkefeld V filter. The fil- trate inoculated into rabbits caused rabies. Celli and de Blasi ® ground the brain and spinal cord in sand under 300 atmospheres pressure. A suspension in distilled water, when sub- jected to a small Berkefeld filter under a vaccuum of 570 mm. for half an hour, gave an infective filtrate. Remlinger (Ann. de I’Institut Pasteur, v. 17, No. 12, 1903, p. 834) confirmed his earlier work with Riffat-Bey mentioned above. He showed that the virus of hydrophobia can not be made: to pass through a Chamberland filter nor through a Berkefeld N or W. It can only be forced through a Berkefeld V, which filter is the most porous of the Berkefeld system. Hog cholera—De Schweinitz,’ in a preliminary note, mentions a disease peculiar to hogs, indistinguishable clinically and at post- mortem from hog cholera, but which can be transferred from hog to hog by inoculation with certain body fluids which have been rendered free from bacteria by filtration through the finest porcelain filters. This filtrate was shown to contain no organisms of hog cholera or swine plague, because when inoculated into rabbits and guinea pigs the animals remained healthy. Rinderpest-—Nicolle and Adil-Bey passed the virus of this dis- ease through a Berkefeld filter, but not through a Chamberland F. Clavelee (sheep pow).—Borrel ¢ filtered a suspension of the pus- tules in water. The filtrate from the Berkefeld filter was infective, but that from the Chamberland F was not. Nonjilterability of vaccine and smallpox.—Parke‘ crushed vaccine virus with fine sand, using 25 tons of pressure to the square inch. One portion of the suspension of crushed virus was passed through a Berkefeld filter and another portion through a Chamberland filter. Both filtrates were evaporated over sulphuric acid in a vacuum. Calves and rabbits inoculated with the filtrate before and after @Remlinger and Riffat-Bey: Le virus rabique traverse la bougie Berkefeld. Compt. rend. heb. des Sec. de la Soc. de Biol., vol. 55, 1903, p. 730. b Deut. med. wochenschr., vol. 29, p. 945. eU. 8. Dept. of Agriculture, Bur. Animal Industry, Circular No, 41, Sept., 1903. ¢ Nicolle et Adil-Bey: Jtudes sur ia peste bovine. Ann. de I’Inst. Pasteur, vol. 16, 1902, p. 56. eBorrel: Experience sur la filtration du virus claveleux. Compt. rend., Soc. de Biol., vol. 54, 1902. f Assn. Am. Physicians: Trans., vol. 17, 1902. 74 evaporation ‘failed to show any reaction. Control animals inoculated with the crushed material before filtration always had successful vaccinations. The object of the crushing was to liberate the organ- ‘isms from epithelial cells or other tissues which might retain them. Smallpox virus from three fatal cases failed after crushing to pass into the filtrate, as determined by the inoculation of monkeys. Filterable bacteria—Von Esmarch * sought to determine whether there are such things as ultramicroscopic organisms among the saprophytes. i We readily believe that the virus of a filterable infectious disease is made of very small organisms, possibly ultramicroscopic, and that if these organisms could be made to multiply the resulting mass would have an appreciable size. If there are ultramicroscopic sapro- phytes he thought that all conditions were in the highest degree favorable for their multiplication, and that on the ordinary labora- tory media they ought to find their most suitable conditions of growth and give an appreciable evidence of their existence. He used 40 different kinds of fluids, including sewage, rich vege- table infusions, decomposing urine, emulsions of sputum, cavaders, and feces. The clear filtrates from these suspensions were planted on all the laboratory media and these plants kept under different conditions showed no growth. During the first week’s observations of the original filtrate no growth was noted; but after ten days this fluid showed a turbidity which was due to a very fine motile organism (Spirillum parvum), which grew as vibrios and spirilla, which were recognized only by the greatest magnification. It passed the Berkefeld, Chamber- land F, Reischel, and Pukall filters and appeared in the first 200-300 cc. of filtrates. No other bacteria were found in the filtrates. Its size is about the same as that of the influenza bacillus, being 1 to 3 micra in length and 0.1 to 0.8 micra in width. Von Esmarch grew bacteria through filters which hold them back in ordinary filtration work. He used Berkefeld, Kitasato, and Maassen filters. These filters were filled with plain bouillon and were placed in a vessel containing bouillon inoculated with an organism, and the whole was kept at 37°, or room temperature. Typhoid grew through the Kitasato filter at 37° in twenty-four hours, and at room temperature in two days. Cholera went through a Maassen filter at 37° in two days, but a control kept at room temperature did not grow through after thir- teen days. A small Berkefeld filter allowed Bacillus prodigiosus to pass in @Centbl. fur bakt., bd. 32, 1902, p. 561. 75 from one to three days, and a large Berkefeld allowed pyocyaneus and prodigiosus to pass in seven days. Wherry ¢ states that the bacillus producing pneumonia in guinea pigs (0.5 micron wide and 0.7 micron in length) passed the small. . Berkefeld No. 5, but was not found in the filtrate from the thicker walled Berkefeld No. 8, nor in the filtrate from the Chamberland F. It, however, grew through the walls of all three. FOMITES. While we made no experiments directly designed to determine the part played by fomites in transmitting the infection of yellow fever, still our work strongly bears on this point, and we can fully corrobo- rate the conclusions of Reed and Carroll that fomites or inanimate - objects are not dangerous in this respect. Nonimmunes whom we kept for weeks under observation in our’ mosquito-proof rooms slept on the same beds, used the same clothing, washed from the same bowl, ate the same food, drank the same water, and breathed the same air as those sick with yellow fever; neverthe- less they remained free of all'fever except that which was purposely given them by mosquito bites or blood inoculations. As these experiments were done in the summer time at Vera Cruz, a badly infected city where the disease prevailed at the time in epidemic form, it removes some of the objections which were made at the time to the work of the Army Commission, which for the most part was done during the winter months in an otherwise healthful locality— Camp Lazear. THE FILTRATION OF MALARIAL BLOOD. The filtration experiments with malaria were undertaken with the hope that they would throw light upon yellow fever, which bears so many analogies to malaria. Both diseases are transmitted by mos- quitoes, and it is therefore natural to suppose that yellow fever is due to an animal parasite, perhaps similar to the well-known plasmodium of Laveran. However, as the one disease is filterable and the other is not; and as the parasite of the one is visible and the other can not be seen with the highest powers of the microscope at present at our command, either in the mosquito or in man; and as the one produces an immunity and the other does not, we find the analogy is not after all so very striking and that it does not seem helpful in solving our problem. The malarial rosette breaks and liberates spores (merozoites) which are exceedingly minute, and in order to carry out the analogy in an «Journ. med. research, vol. 8, 1902, p. 322. 76 experimental way we filtered malarial blood in order to determine whether there might be forms of the malarial parasite which are even smaller than this spore. We know from the work of Novy that a trypanosome (7 rypano- soma Lewisi), which is a colossal organism when compared with a malarial spore, has forms which are so minute that they pass a Berkefeld filter, for he has succeeded not only in artificially culti- vating the adult trypanosome parasite, but in infecting animals with the filtrate from these cultures. We also know from the recent work of Schaudinn® that some of the animal parasites (Spirochaeta), multiply by reducing division; that is, each time cleavage takes place the organism is reduced in size, and this process continues until the divided forms become too small to be seen as individuals and can be made out only as clusters. We therefore reasoned that if the malarial parasite has an ultra- microscopic form minute enough to pass the pores of a filter, it would encourage us very much to look for a visible form of the yellow fever organism in the blood and tissues of man and the mos- quito by the aid of technique that had not previously been employed. Our filtration experiments with malarial blood resulted negatively so far as demonstrating the presence of a minute or ultramicroscopic form of this parasite was concerned, but there developed unexpectedly what appears to be a demonstration of the malarial toxin. We pro- duced a definite paroxysm by the inoculation of blood serum freed of the malarial parasites by filtration; and it is reasonable to suppose that the same substance circulating in the blood, which caused the chill, fever, and sweat in one man, caused a precisely similar chain of symptoms in the other two into whom this serum was transferred. We found that if the blood is drawn after the height of the parox- ysm and while the fever is declining this poison is not manifest; but if the blood is taken during the chill and while the temperature is rising, it is present. If this poison is the toxin causing a malarial paroxysm it is remark- able that it should be present in the blood serum in such a considerable quantity and disappear so very rapidly. Still, the clinical symptoms of the disease would indicate the sudden production of a large quan- tity of toxin and its rapid elimination, neutralization, or destruction. So far as we know, this is the first time that a poison has been demon- strated which is capable of reproducing the symptoms of a disease due to an animal parasite of microscopic size. Tt would be folly from a few observations to claim that we have dis- covered the malarial toxin. The only conclusion justified is that we have demonstrated the existence of some poison in the blood which is ¢ Loe. cit. 77 capable of reproducing the symptoms of the disease when injected into the veins of other men. We are not unmindful of the fact that chemical substances derived from the hemoglobulin or other proteids in the blood may be toxic, and we are of course familiar with the work of Gauldi, Montesano, Mannaberg, Celli, and others, who failed to demonstrate a pyrogenic toxin in malarial blood from similar experiments. The length of time the blood was exposed to the air between the time it was drawn -from the malarial patient until it was injected into the person experi- mented upon may account for the discrepancies in results. The time the blood is drawn in relation to the paroxysm and many other factors should also be taken into account. Mannaberg? drew blood during the attack in a case of ordinary tertian malaria. He centrifugalized it and injected the clear serum subcutaneously into two healthy people. One received 1 cc. of serum at 4 p. m., when his temperature was 36.7° C. The temperature at 4.30 p. m. was 87° and at 6 o’clock 36°. The other patient was given 0.7 cc. of the serum and his temper- ature rose within fifteen minutes after the injection from 36.5° to 87.6° C. ; Celli ® took during the cold stage a small quantity of blood from each of many malarial patients. Young children were inoculated with 50 cc. of the serum sub- cutaneously and 50 cc. intravenously. Another child was given the concentrated serum remaining after treating 260 cc. of serum in a vacuum apparatus at low temperature. The child was injected intravenously and subcutaneously. From a hemorrhage in a case of severe comatose pernicious malaria 25 cc. of serum were obtained and injected into another patient. None of the patients into whom the serum was injected showed pyrexia. There was in several instances, however, a slight rise of temperature which the experimenter says may occur after the injec- tion of normal serum. Rievel and Behrens ¢ studied a sarcosporidium of the llama. They. removed ten of the sacks and ground them up with physiological salt solution in a mortar, and injected 2 cc. of the fluid subcutaneously into a rabbit. After seven hours the rabbit died. The autopsy revealed nothing unusual. @Mannaberg, Julius: Die malaria krankheiten. Nothnagel’s Specielle Path- ologie und Therapie, Bd. 2, 1899. bCelli, Angelo: Malaria. Transl. by J. J. Eyre. Longmans, Green & Co., New York and London, 1900. ¢ Rievel and Behrens: Beitriige zur Kenntnis der Sarcosporidien und deren Enzyme. Centralblatt fiir bakt. u. parasit. (orig.). Bd. 35, no. 3, s. 341. 78 Another rabbit received by mouth the contents of several sacks rubbed up in salt solution. This rabbit was given at the same time a subcutaneous injection of 1 cc. of the fluid. The animal died after eight hours. From a gross examination of his internal organs and a bacteriologic examination of the same, nothing abnormal was found. Blood from the spleens of the above-mentioned rabbits, ‘when injected into three other rabbits, caused no abnormal symptoms. ' Pieces of the flesh of the llama were cut up in salt solution and the fluid part was injected into two rabbits subcutaneously. Both remained sound. A rabbit inoculated subcutaneously with a suspension of the con- tents of sarcosporidia sacks in salt solution died after seven hours. The post-mortem was negative. Two other rabbits treated in the same way remained alive six hours. Another died after seven hours. A suspension was subjected to dialysis and it was found that the dialysat, when injected into a rabbit, caused death within twenty- four hours. The cooked dialysat was inactive. Our experimental cases in malaria follow: Fiurration Experiments with Esrivo-AuTuMNAL FeEver. Filomena Martinez (case LXIIT), 35 years old, born in Mexico City, lived in Vera Cruz about one year. The patient was admitted to the hospital of Working Party No. 2 October 27, at 10 a. m. He had been under observation the previous day and early that same morning at San Sebastian Hospital. As he showed a heavy infection with malarial parasites he was transferred to our laboratory. He gives a history of having had yellow fever about six months ago. His present illness, according to his statement, began some two weeks ago with fever, but he says he did not have chills. The patient’s mental condition when seen was below par, and he wag unable to give consistent answers. He seemed somnolent and was evidently begin- ning to show the effects of his infection upon the brain. An examination of his blood, taken at 4.15 p. m., October 26, showed very many young ring forms, some of. them with active amceboid shapes. None appeared pigmented in the smears stained with Goldhorn’s polychrome methylene blue. Crescents and ovoids also present. At 12 o’clock noon, October 27, a trifling incision was made through the skin over the median cephalic vein on the right side. A needle was introduced into the vein and 100 ce. of blood were quickly drawn into a sterile flask. The wound was covered with a sterile dressing and healed without complications. " 79 The blood was immediately put into the ice chest, the temperature of which registered between 16° and 19° C. Clotting took place rapidly. The red cells settled to the bottom of the flask, the upper part of the clot being composed of a firm yellowish buffy coat. The serum separated well and was very clear. The blood serum was drawn off and diluted with an equal volume of an isotonic salt solution and then divided into two portions. CASE. FILOMENA MARTINEZ. 27 28 Temperature chart of Filomena Martinez. One portion was passed through a Chamberland B filter and in- jected into José Ojeira. The other portion was passed through a Berkefeld filter and injected into Luis Peredo. Blood smears made from the blood which was drawn from the vein showed in stained specimens crescents and the young small ring forms of estivo-autumnal malaria. Some of the stained parasites showed one chromatin point, others two. A few were irregular in outline, 80 EXPLANATION OF PLATE 2. Estivo-autumnal malaria. The character of the malarial parasites in the blood of Filomena Martinez at the time it was filtered. Stained with Goldhorn’s polychrome methylene blue. 1. Small ring forms. 2. Young ameboid forms. 3, 4, 5, and 6. Ovoids. Plate 2. CHARACTER OF THE MALARIAL PARASITES IN THE BLOOD OF FILOMENA MARTINEZ AT THE TIME IT WAS FILTERED. 81 indicating older parasites with ameboid motion. These latter were two or three times the size of the small ring forms. (See plate 2.) These irregularly shaped parasites had two and some three chro- matin points. In the blood taken at subsequent periods similar forms were seen, the older or younger forms predominating, depending upon the time of day the blood was examined. The details of diluting and filtering the blood serum of Filomena Martinez follow: At 5.30 p. m. the blood was taken from the ice chest, having been there just five and one-half hours, and 27 cc. of the clear serum were pipetted off. This serum contained a few flakes and very few red blood cells. To this serum was added an equal amount (27 cc.) of physiological salt solution (0.6 per cent). The mixture was transferred to a filter flask and a Chamberland B filter was carefully lowered into the fluid and securely fastened in position. This was a new filter marked as follows: “B. filtre Cham- berland systéme Pasteur H. B. Cie., Choisy-le-Roi. BTE S. 6.0.G. Contrélé.” The filter was tested before using with an air pressure of 30 pounds, after which it was lowered into water. When first lowered into the water the air came from every part of the surface of the filter in very fine bubbles, but nowhere was there evidence of a crack or pinhole. As goon as the filter became wet no air could be forced through it with a pressure of 30 pounds. This particular candle was consid- ered to be tighter than the other Chamberland-Pasteur filters which we had similarly tested. The filter was then thoroughly washed by allowing 200 cc. of water to pass through it under 20 pounds pressure. It was sterilized in the hot air sterilizer for one hour on the day before the blood was filtered, at a temperature of 150° C. for one hour. The filtration was begun at 6 p. m., October 27, and was conducted in accordance with the diagram (fig. 2) by means of pressure from an air pump. This air pump was worked by hand and the diluted blood serum filtered under a pressure of 15 pounds. The pressure was controlled by the gauge, as shown in the sketch. Very slight variations occurred both above and below 15 pounds, owing to the difficulty of exact control with hand power. The pressure was kept up for one hour, and the filtrate was drawn from the inside of the bougie with a long sterilized pipette. In this manner it will be noticed that there was no possible chance of contact between the filtrate and the blood serum, and throughout the process the greatest care was taken in order to prevent such a contamination. The filtrate as it came through the filter was clear and of amber color. 82 At 7.20 p. m. 20 cc. of the filtrate were injected by means of an appropriate syringe with hypodermic needle into the left median cephalic vein of José Ojeira with entirely negative results. A second portion of the blood serum of Filomena Martinez was _G PP ugie B. PP, pressure pump. G, pressure held in place by a rubber stopper. P, a ‘face of the filter. B, the blood serum. stopped with cotton and sterilized; keep the small quantity of blood in contact with the sur Fia. 2—The arrangement used for filtering through a Pasteur-Chamberland bo’ gauge. D, Pasteur-Chamberland bougie, \ t | | | | | ea oD a uN ae 4 Ti a SAH Toes Qa es 56 a> ASSN) oe ROMA i (SE | I 9 itl i 3 i pipetted off and diluted with an equal quantity of physiological salt solution, and filtered through a small Berkefeld filter, as follows: -A new Berkefeld filter was prepared by thoroughly washing by allowing water to pass through it for several hours, and then ster- ilized in dry heat. 83 ‘eISnoq, preyexsog ‘q ‘WNAes poolq oy} SulurezUOO ysepy ‘V ‘dund puvy ‘q ‘snjd 104400 ‘9 - ‘dund wnnova puvy v jo suvem Aq 10}[9 pleyoyiog B@ Ysno1g} Sulsey[y Jo poyjem oy} Surmoysg—‘g “Ol od je = oe ee | _—— oe oe eee) — a ae 84 This filtration was also done from without inwards, as may be seen by reference. to the sketch (fig. 3), but by using vacuum instead of direct air pressure, as in the case of the filtration iirongh the Pastenr- Chamberland bougie. The filtrate was carried over to a sterile bottle, as shown in the sketch, and drawn out with a pipette, so that, care being taken, there could be no chance of contamination. It reaived about twenty minutes to filter 46.5 cc. of diluted serum, and at 8.15 p. m., viz, eight and one-fourth hours after the blood was drawn, twenty cubic centimeters of this filtrate, which represented 10 cc. of the original serum, were injected into the left median basilic vein of Luis Peredo with entirely negative results. This filter was then thoroughly washed with water which ran through in drops under atmospheric pressure, and was preserved for further testing, with the following results: On March 1, 1904, this filter was tested with a bouillon culture of Staphylo- coccus pyogenes aureus. The filtrate remained sterile after ten days in the incubator. . At 10 p. m. Martinez was given 1 gram of bimuriate of quinine directly into one of the veins of his arm. This was repeated at noon on October 28, and again at 11 p. m. on the same day. On the 29th he received another gram into the vein, with marked improvement in his symptoms and a notable reduction in the number of intracorpuscular forms in the blood, as will be seen by the following _ notes of the case: October 27,10 p.m.—One gram bimuriate of quinine intravenously. Blood examination, 3 crescents in one field; some fields have as many as half a dozen small ring forms. October 28, 2 a. m.—Blood examination. Some fields have 5 and 6 small ring fans some irregular amoeboid shapes, also ovoids. 6 a. m.—Blood examination. One or two ring forms to each field; also, crescents. 10 a. m.—Blood examination. About 1 organism to each field; some young ring forms; some amceboid shapes ; also ovoids. 12 noon.—One gram bhoueiate of quinine intravenously. 2 p. m.—Blood examination. About 1 intracorpuscular form to each field. 11 p. m.—One gram bimuriate of quinine intravenously. October 29, 2 a. m.—Ten-minute search of a slide stained with polychrome methylene blue showed no intracorpuscular forms; cres- cents not diminished in numbers. 6 a. m.—Only 2 intracorpuscular rings seen; crescents in moderate numbers. 10 a. m.—Given 1 gram bimuriate of quinine into a vein. Five- minute search of a stained blood smear shows 5 ovoids and only 1 intracorpuscular ring form. 85 2 p. m.—No intracorpuscular forms. 10 p. m.—No intracorpuscular forms. October 30, 6 a. m.—Blood examination shows no intracorpuscular forms. A large mononuclear leucocyte has much brown pigment. Ovoids still present in apparently undiminished numbers. Patient has very much improved in his general condition. His mind is better, appetite has returned, and he was returned to San Sebastian Hospital. FintraTion EXperimEents with Tertran Fever. Andrez Mendez (case LXVT), 39 years old; born in La Luz, Estado de Guanajuato; never had fever in his native place. In 1878 had yel- Case. | Anores Menpez. DousLe TERTIAN MALARIA. v2} Mo 6 # 8 of A.M. P.M. Pulse. Temperature chart of Andres Mendez. low fever (?) in San Antonio, Estado de Guanajuato, with which he says he was sick about one month. He came to Vera Cruz three years ago and has had fevers five or six times since. 86 _ Present illness dates from about November 3, but states that he has been troubled with mild attacks of fever for a month, which he describes as coming on alternate days, but not sufficiently severe to keep him from his work. The fever which initiated his present sickness began with a severe chill, and was followed by fever and sweat, and was associated with some nausea and vomiting. He states that these paroxysms were repeated daily until his admission to San Sebastian Hospital, Novem- ber 6, 1908. ‘ Blood examination showed that he had a heavy infection with tertian parasites, and he was immediately transferred to the labora- tory of Working Party No. 2, Yellow Fever Institute. The man was physically snalusls but very anemic, mucous mem- branes particularly pale, skin cold aul damp. At about noon on this date (November 6), the patient was seized with a chill. By 12.30, half an hour later, the rigor was very marked; he lay in ‘bed with a blanket drawn over his head, and was shaking violently; he could not hold a thermometer in his mouth, and the pulse was taken with difficulty. During this time the temperature was rapidly rising, it being now 39.1° C. At 12.40 blood was drawn from one of the superficial veins at the bend of the elbow. On account of the rigor there was some difficulty in introducing the needle. The blood flowed freely; 125 cc. were quickly drawn. It was permitted to flow into a porcelain dish and immediately defibrinated by whipping with sterilized forks. Clotting took place very quickly, so that the fibrin was readily and quickly separated from the fluid. Judging from the size of the clot and color the fibrin had enmeshed a number of corpuscles. The defibrinated fluid showed no further. tendency to clot, and on microscopical examination looked like fresh blood containing a normal number of corpuscles. To 25 cc. of defibrinated blood was added 25 cc. of physiological salt solution, and this diluted blood was filtered through the same Berkefeld filter in the same manner as was done with the blood of Filomena Martinez (see p. 84). This filter, when tested later, March 1, 1904, held back Staphylococcus pyogenes aureus. Nine ce. of the filtrate were injected into the right basilic vein of Luis Peredo as soon as this amount could be obtained. This injection took place at 1.40 p.m. It only took about forty minutes to defibrin- ate and filter the blood, which process was done as rapidly as possible. Stained smears of the filtrate showed no morphologic elements. The filtrate had a distinct red color. For the method by which this filtration was done, see fig. 3. As a control, José Ojeira, at 2 p. m., was given an injection into Plate 3. CHARACTER OF THE MALARIAL PARASITES IN THE BLOOD OF ANDRES MENDES AT THE TIME IT WAS FILTERED. EXPLANATION OF PLATE 3. Double tertian malaria. The character of the malarial parasites in the blood of Andres Mendez at the time it was filtered. Stained with Goldhorn’s polychrome methylene blue. 1. Young ameboid forms. : 2. Older pigmented parasite. 8. Young and old forms in the same field. 4, 5, and 6. Segmenting forms. 88 his left basilic vein of 4 cc. of the unfiltered mixture. As the blood was diluted with equal parts of salt solution, he therefore received 2 cc. of Mendez’s blood. The unfiltered mixture of defibrinated blood and salt solution, upon microscopic examination shortly after Ojeira received his injection, showed amoeboid tertain organisms with dancing pigment. For the character of the malarial parasites infecting the blood of Mendez, see illustration, plate 3. After drawing the blood from Mendez he continued to have a chill, with severe rigor and chattering of the teeth, accompanied by nausea and vomiting. His temperature continued to rise after the blood was drawn until it reached 40.2° C. The febrile period was followed by drowsiness and moisture of the skin. As will be seen by reference to the temperature chart, Mendez was kept under observation without quinine, and had another typical malarial paroxysm the next day. All the evidence in his peripheral blood, which was examined frequently, pointed to a severe double infection with the tertian parasite. He was then given quinine, which entirely controlled the disease, and caused the complete disappearance of the parasites from his peripheral blood. The results caused by the injection of the blood of Andres: Mendez into Peredo and Ojeira follow: Luis Peredo (case LXIV), a volunteer, aged 25, born in Jalapa, State of Vera Cruz, where he has always lived. When examined at Jalapa, August 26, he was found to be physically sound; urine con- tained no albumin; peripheral blood showed no plasmodium. He was brought to Vera Cruz August 28 and taken from the station directly to the laboratory, from which time he was kept constantly within a mosquito-proof room. On October 27, after -having been under daily observation two months, during which time he remained in normal health, he was injected with the filtered blood of Filomena Martinez (page 84), who at the time was suffering with a paroxysm of malarial fever of the estivo-autumnal type, his blood containing many young ring-forms and crescents. It will be noted by reference to the records of Filomena Martinez that the blood was drawn during the decline of the paroxysm. It was then allowed to clot in the ice chest; the clear serum was pipetted off and diluted with an equal quantity of isotonic salt solution, and this filtered through a new Berkefeld filter. Twenty cubic centimeters of the filtrate, which on account of the dilution represented 10 cc. of the blood serum, were injected into the left median basilic vein of Peredo. 39 For further details of the manner in which the blood serum was obtained and the filtration performed, see the above records of Filo- mena Martinez. Peredo was carefully watched from the hour he was injected, but he remained in good health, and no deviation from the normal was detected. His temperature was taken every four hours during the night and day, both before and following the injection, as will be seen by the temperature chart. No symptoms developed. ‘His blood was examined daily for plasmodium, but none was found. The result of this injection must therefore be considered negative. Ten days later he was again injected with filtered malarial blood under different circumstances, and with positive results. At 1.40 p. m., November 6, he was given an intravenous injection of the blood of Andres Mendez, passed through the same Berkefeld filter as before. Mendez was suffering with a double tertian in- fection; his blood was drawn during his chill and before the height of the paroxysm, as will be seen by reference to the temperature chart (page 85). Thinking that allowing the blood to clot four or five hours in the ice chest in order to obtain a clear serum for filtration might be too severe a tax upon the vitality of the malarial parasite, we this time defibrinated the blood as quickly as possible, diluted it as before with an equal volume of physiological salt solution, and filtered it through the same Berkefeld filter in the same manner as was done with blood of Filomena Martinez. As soon as 9 cc. of the filtrate could be obtained it was inj jected into the basilic vein of the right arm of Louis Peredo. This injection took place at 1.40 p. m. About thirty-five minutes after receiving the injection he began having chilly sensations and headaches, and presently went to bed covering himself with his blanket (2.25 p. m.). Five minutes later (2.30) he was having a violent chill, his teeth chattering so that we could not trust the thermometer in his mouth. The rigor of the entire body was so marked that there was difficulty in taking the radial pulse. The face was pale, and at this time he vomited most of the dinner he had eaten a short time before receiving the injection. The patient complained of headache, which he localized at the fore- head and occiput; says he felt cold and had pains in the knees. At this time the skin was diy. The chill lasted somewhat over half an hour. At 3 p. m. the patient had transient chilly creeps, very slight rigor. ' At 3.15 p. m. he said he felt “ warm inside,” and all sense of chilli- ness had disappeared; still has headache. At 3.25 p.m. he complained of marked pain in the legs. 90° At 3.30 p. m. vomited the remainder of his dinner. It will be seen from the temperature chart that during this time his temperature was rapidly. rising and reached its highest point (38.7° C.) at 4 o’clock p. m., just two hours and twenty minutes after receiving the injection. . The pains in the knees and back continued, and nausea and vomit- ing now became a distressing feature of the paroxysms for the patient. The fever gradually subsided, and reached normal at 4.30 a. m. that same night. (See temperature chart.) As the fever subsided the skin became moist, the nausea and pains gradually disappeared, so that by 6 o’clock p. m. the patient was quiet and dozing. The entire paroxysm, therefore, according to the tem- perature record, lasted about eight hours, although the patient was sleeping quietly five hours after receiving the injection. It is interesting to note that this man Peredo had what seemed to be a typical malarial paroxysm beginning with a distinct rigor asso- ciated with a rise of temperature and followed by slight sweating. It is of particular interest to note that his paroxysm, so far as symptoms were concerned, was very much like the paroxysm from which Andres Mendez suffered, especially the nausea and vomiting. Peredo was kept under very close scrutiny until November 24, eighteen days following the injection, during which time he remained entirely normal and no plasmodium appeared in his peripheral blood, which was frequently examined, as follows: Blood examination.—Goldhorn’s stain. November 6.—4.30 p. m., 8 p.m. No malaria. November 7.—4.30 a. m., 8.30 a. m., 12.30 p.m, 5 p.m.,11 p.m. No malaria. November 8.—7 a. m., 1 p. m., 6 p. m., 9.30 p. m. No malaria. November 9.—7.30 a. m., 1.30 p. m. No malaria. November 10.—2 a. m., 3.30 p. m., 8. p. m., five minutes each. No malaria. November 11.—4, 7, 10 a, m., 2, 6, 11 p. m., five minutes each. No malaria. November 12.—1.30, 6.25 a. m,, five minutes each. No malaria. ‘November 13.—7 a. m., 9.30 p. m., five minutes each. No malaria. November 14.—8 a. m., 8 p. m., five minutes each. No malaria. November 15.—8 a. m., 8.30 p. m., five minutes each. No malaria. November 16.—7 a. m., 9.30 p. m., five minutes each. No malaria. November 17.—8 a. m., 8 p. m., five minutes each. No malaria. _ José Ojetra (case XXIII), a volunteer from Jalapa, 18 years old; had never lived on the coast, and says he never had fever of any kind. On examination in Jalapa, August 11, he was found to be physically sound, of robust physique; urine showed no albumin, and blood exam- ination for malaria was negative. He was taken to Vera Cruz August 13, and immediately trans- ferred to a mosquito-proof room in the laboratory, where he was kept under close observation. Paroxysm CASE Luis PeReoo. gee es 22 23 24 of AM. PM. 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The man was kept under close observation in a mosquito-proof room, but showed no reaction. There was no rise of temperature, nor did he present any untoward symptoms. On October 27, 7.20 p. m., he received intravenously 20 ce. of diluted blood serum of Filomena Martinez (estivo-autumnal infection), passed through a Pasteur-Chamberland filter B. This represented 10 ce. of blood serum. For detals of this filtration see Filomena Martinez (p. 81). Ojeira showed no reaction whatever as a result of this injection. It will be noted that the blood of Martinez was drawn after the height of the paroxysm, and while the temperature was on the decline. Martinez was suffering with a very severe #stivo-autumnal infection at the time the blood was taken. Ojeira’s blood was carefully examined several times daily, both be- fore and following this experiment, and at no time was anything resembling a malarial parasite seen in his peripheral blood. On November 6, the patient having continued in good health since the last experiment, was used as a control for the experiment made on Peredo. On this date, at 2 p. m., he was given an intravenous injection of 4 ce. of the unfiltered, diluted, and defibrinated blood of Andres Mendez. At the time the blood was drawn from Mendez it contained a heavy infection of a double tertian malaria, and the blood was taken from him during a chill and before the height of his paroxysm. It was at once defibrinated, diluted with an equal volume of physiolog- ical salt solution, and filtered through a Berkefeld filter. Nine cc. of the filtrate were given intravenously to Peredo, causing a malarial paroxysm without, however, the presence of the malarial parasite, and due, as we believe, to the toxin (?) in the blood of Mendez. Ojeira, who received 2 cc. of unfiltered blood (4 ce. dilution), reacted within an hour, with a slight rise of temperature and nausea, and four days following developed a typical malarial paroxysm, with many tertian parasites in his peripheral blood. There can be no doubt that the reaction to the 2 cc. of defibrinated blood injected into the vein of Ojeira caused a slight paroxysm, which it is reasonable to suppose was due to the same poison present in the blood of Mendez, and which also caused the reaction in Peredo. It will be noticed that 2 cc. of this blood caused but a slight reac- . tion in the case of Ojeira, while 4.5 cc. caused a more marked reac- tion, with a rise of temperature to 38.7° C., in the case of Peredo, 92 indicating in a very definite manner that the severity of the symp- toms were directly due to the quantity of poison introduced. Ojeira did not, have a chill or other manifestations of a malarial paroxysm, other than a rise of temperature and nausea. He vomited gastric mucus several times. a On November 10, the fourth day following the injection, Ojeira had a typical malarial paroxysm, with tertian parasites in his periph- eral blood. He suffered with a double infection, having a chill every day, as will be noticed by reference to the temperature chart. The character of the parasites in his blood and the clinical course of the disease resembled in all respects those of Mendez, from whom the blood was taken. Both cases were entirely controlled by quinine. MISCELLANEOUS OBSERVATIONS ON MOSQUITOES. In association with Doctor Goldberger we made some miscellaneous observations upon the life history and biology of the Stegomyta fasciata and Culex pipiens, some of which were of sufficient interest to record. We found that the female Stegomyia does not always lay her eggs at one time. More often she deposits them in groups at intervals of several days. The maximum number laid by any one insect observed by us was 101. The female Stegomyia sometimes dies, apparently from exhaustion, after laying her eggs, but we noted several instances in which this was not the case. The insect which laid 101 eggs was alive and vigorous until killed by us five days later. The manner in which the female Stegomyia lays her eggs is of some interest. She bends her abdomen ventrally, and as the genital orifice comes in contact with the sides of the vessel or with the water or other object the egg is deposited. The insect moves along and repeats the performance. The eggs are sometimes laid on the water, sometimes on the side of the vessel above the water line, and sometimes on a leaf floating on the water. In accordance with the few observations which we made on this particular point, Stegomyia fasciata females that are fed solely on banana or sugar do not lay eggs. They seem to require a feeding of blood for ovipositing. Unconjugated females also do not lay eggs. The longest life that we observed was in a female Stegomyia, which we kept for sixty-four days, and then killed for sectioning. _ We found, as has been often noted by other observers, that the greatest activity of the Stegomyia fasciata is during the daytime, but we have observed them flying at night. We have also observed them feeding on us at night by artificial light. We have noticed on several occasions that they are especially voracious early in the morn- 93 ing, about sunrise. On several occasions a number of noninfected insects were let loose in the laboratory and we observed that upon ris- ing at sunrise they attacked us viciously. It may be noted that this fact apparently explains the danger to persons sleeping in an infected house and the comparative freedom from danger in daylight communication with an infected town, especially if the person remains in the open air and sunlight and avoids houses, and confines his visits to the streets and parts of the town free from the disease. . A number of experiments were made with the female Culex pun- gens, but they could not, under any circumstances, be induced to feed upon blood while in confinement. It was found that they preferred death. * MOSQUITOES MAY BITE CADAVERS. The female Stegomyia fasciata will bite a cadaver, and, if on a dependent portion, can draw blood. We havé two observations on this point. Narciso Nadal (case XX). A number of Stegomyie were applied twelve hours after death, only one of which apparently obtained blood. Trinidad Martinez (case XXII). A number of female Stegomyiv fasciate were applied one-half hour after death, and three insects succeeded in feeding with blood. As it has been shown by the work of the French commission that the blood of yellow fever is not infective after the third day, the danger of conveying the infection by means of mosquitoes feeding upon cadavers must be exceedingly remote. LonGEVITY. Several experiments were undertaken to determine the fact whether the male Stegomyia fasciata, as has been stated, has a brief life his- tory. We have one experiment showing that the male mosquito may live and thrive over a month. Observation —A number of male mosquitoes were placed in a cage October 10 and subsequently fed on sirup. They were all alive and in good condition on November 15, when they were killed and used for experimental purposes, having lived thirty-six days. Ovirosrrinc. Sometimes the female Stegomyia fasciata will lay a considerable number of eggs at one time and then die. Observation.— (Mosquito XLIII. Francis, Re. No. 4.) This female Stego- myia fasciata was taken from the breeding jar on- October 8, fed on normal blood October 4, 6, 7, 8, and 10, then placed in a jar with water to tempt ovi- positing, and banana feeding begun. On October 19 four males were added to the jar. On October 23 the female was given another blood feed. On the 26th 94 she laid 54 eggs and was found exhausted and dying on the surface of the water. More often the female Stegomyia lays groups of eggs at intervals of several days, and sometimes lives after the last laying. Observations.—-(Mosquito XLIII-38. Francis, Re. No. 1.) This female Steg- omyia was taken from the breeding jar October 3; fed on normal blood on October 4, 6, 7, 8, and 10; then placed in a jar to tempt ovipositing and given banana; laid eggs on October 10 and 11; given another blood feed October 16; found apparently dying on the surface of the water on October 18. (Mosquito XLIII-68. Francis, Re. No. 3.) This female Stegomyia was taken from the breeding jar on October 3 and fed on normal blood October 4, 6, 7, §, and 10. It was then placed in a jar to tempt ovipositing and given banana. On October 11 she laid a considerable number of eggs. On October 19 again given blood feed and three males placed in the jar. October 25 she laid 29 eggs. On October 26 laid 12 more eggs. On the 30th the insect was removed in a dying condition. (Mosquito XLIII-67. Francis, Re. No. 5.) This female Stegomyia was taken from the breeding jar October 3. Fed on normal blood October 4, 6, 7, 8, and 10. Then placed in a separate jar with water to tempt ovipositing and given banana. On October 13 she laid some eggs. On the 19th given a blood feed and three males added. She ‘laid 11 more eggs on October 23, 16 on the 25th, and 37 on the 28th, when she was found dying on the surface of the water. (Mosquito XLIII-69. Francis, Re.) This female Stegomyia was taken from the breeding jar when less than forty-eight hours old and fed upon normal blood October 4, 6, 7, 8, and 10, and subsequently at intervals of one or two days up to October 23, when she was placed in a cage by herself with a beaker of water to tempt ovipositing. At the same time given banana to feed upon. October 25 two males were added to the cage. October 25 she laid 51 eggs; November 7, 24 eggs; November 8, laid 26 eggs; total, 101 eggs. She was given another feed of blood November 10. Was killed November 13 while apparently vigorous. Female Stegomyia fasciata that have fed on the blood of yellow- fever patients on the second, fourth, and sixth days of the disease may subsequently lay eggs that hatch in a normal manner, and the larve develop into pupz and imagoes. Observations.— (Mosquito XLVII-36. Marcial Lujan, Rx. a.) This insect was separated from the breeding jar October 8 and fed on Marcial Lujan, a typical case of yellow fever on the sixth day of his illness. She was subse- quently fed on normal blood October 11, 13, 16, 17, and 19. On October 22 a beaker of water was placed in the cage in order to tempt ovipositing, and banana feeding begun. She laid 15 eggs on October 25 and 15 more on October 26. Both sets hatched. o (Mosquito XLYII-87. Marcial Lujan, Rx.b.) This female Stegomyia taken from the breeding jar October 8. Fed on blood of Marcial Lujan on the sixth day of his illness, October 9, and subsequently on normal blood October 11, 13, 16, 17, and 19. On October 22 given a beaker of water to tempt ovipositing and banana feeding begun. She laid 31 eggs on October 26, 9 on the 27th, and 12 on the 30th. The eggs laid on the 26th and 27th hatched on the 29th. (Mosquito XLII-122. Marcos Cruz, Rn. 1.) This insect was separated from the breeding jar Octo>er 14 and allowed to feed on Marcos Cruz, one of our experimental cases of yellow fever October 15, that is, on the second day of his 95 illness. She was subsequently fed on sirup. On November 1, placed in a cage with a beaker of water and two males. She laid 12 eggs on November 4, which subsequently hatched. (Mosquito LVIII-32. Sesoleda Martinez, Rx. b.) This female Stegomyia... was separated from the breeding jar October 19. ed upon the blood of Sesoleda = Martinez, a fatal case of yellow fever October 20, the fourth day of his illness... Subsequently this insect was given banana. October 28 a normal blood feed. On November 5 a beaker of water was placed in the cage to tempt ovipositing. Four days later, November 9, she laid 2G eggs, which subsequently hatched. The statement has been made that the female Stegomyia fasciata, and mosquitoes generally, require a feeding on blood in order to lay eggs. In three experiments tried by us we are able to confirm this statement so far as the Stegomyia fasciata is concerned. The insects were fed on sirup and banana, but could not be tempted to lay eggs. Observations.—Banana feeding. A large number of male and female Stego- myia fasciata that had been fed on banana for fourteen days were given a beaker of water to tempt ovipositing. They were Jeft nine days. No eggs laid. 'They were then killed for section. ‘ Sirup feeding. A large number of male and female Stegomyie that had been fed on sirup for fourteen days were given a beaker of water to tempt ovipositing. They were observed twenty-one days later. No eggs were laid. Banana and sirup feeding. A large number of male and female Stegomyia were given alternate feedings of banana and sirup for thirty-two days, at which time a beaker of water was placed in their cage to tempt ovipositing. They were observed nine days later. No eggs were laid. Unconjugated females do not lay eggs. Observations.—Stegomyie pup were isolated and placed in separate small bottles so that the imagoes could not be kept in strict quarantine. Six of these unconjugated females were given a feeding of blood twenty-four hours after birth, and were subsequently fed on banana. They were kept in a cage with a beaker of water to tempt ovipositing. Five days subsequently they were given a second feeding on blood. Twenty-five days later they were killed, not having laid eggs. Size oF ScREENING. 4 It is of considerable practical importance in quarantine and public health work to know the size of screening that will keep out the Stegomyia fasciata, and as no accurate observations upon this subject had been made, with which we were familiar, we conducted a few experiments to determine this point. Screens with a varying number of meshes to the inch were placed over breeding jars, and banana, sirup, and other food placed on the other side so as to tempt the hungry insects to pass through. These experiments were arranged by placing the fruit and food in a jar which was inverted over the breeding jar. Subject passed from observation after 5 days. A factor in the problem which is of prime importancé and whic must always be reckoned with in estimating the value of negativ results is the susceptibility to the disease of the subject used for th inoculations. We were careful to select only those who we were sa’ isfied never had had the disease. Another factor which must be considered is temperature. No mer tion is made in the paper of Marchoux and Simond at what tempers ture their mosquitoes were kept. Our mosquitoes were kept unde artificial conditions at a temperature of between 80° and 90° F. (Se p- 109.) : Many other factors which we shall not discuss undoubtedly ente into and affect this problem. DETAILS OF EXPERIMENTS, In our study we used three sets of Stegomyia fasciata, comprisin, fourteen insects, the progeny of three mothers that had fed on yellov fever. The history of these mosquitoes is as follows: Set 1, Groups I and 11, mosquitoes Nos. 1, 2, 3. and 4. Mother mosquito.—The mother mosquito of this set was one of : number raised from the larval stage in our laboratory, and, withou any prior feeding, was made to sting, on October 3, at 5.20 p. m., : patient (Melancon) with a severe case of yellow fever, 144 hours afte: _ the initial chill; about 42 hours later this mosquito was again mad 109 to sting the same patient, now about 56 hours after the onset. On October 14, at 3.55 p. m., this insect was made to sting a second yel- low fever patient (Kippers), suffering from a severe attack of the disease, about 48 hours after the onset of the first symptoms.¢ In all, then, this mosquito had three feedings of yellow fever blood from two severe cases in the early stages of the disease. This, as well as all our mosquitoes, was kept in a room in which the temperature was artificially kept between 80° F.and 90° F. Four or five times through- out the course of these experiments the temperature in this room fet to 70° for six or eight hours at a time. Group I.—On October 17, at 8.30 a. m. (134 days from the first, 114 days from the second, and ahont 24 days from the third feed of yellow fever blood), this mosquito deposited eggs from which there were hatched between November 4 (4 p. m.) and November 5 (8.30 a. m.) two? adult female Stegomyia fasciata, hie comprise our Group I of Set 1, and were numbered 1 and 2. Group IT.—On October 19, at 4.30 p. m. (16 days from the first, 14 days from the second, and got 5 days from the third feed of yellow fever blood), this same mother insect laid a second batch of eggs from which were hatched between November 7 (8 a. m.) and November 8 (8.30 a. m.) two adult female Stegomyza fasciata, which comprise our Group II of Set 1, and were given the numbers 3 and 4. eo Set 2, Group I, mosquito No. 6 Mother mosquito.—The mother mosquito of this set was one of a number raised from larve and for some time fed on immune blood. On October 4, at 9 a. m., this insect was made to sting a severe case (Melancon) of yellow fever 30 hours after the initial chill.¢ Group I.—October 19, at 4.30 p. m. (15 days after the feed of yellow fever blood), this insect laid a batch of eggs from which there was hatched between November 7 (8.30 a. m.) and November 9 (8.30 a. m.) one adult Stegomyia fasciata, which was given the number 5 and was the only one comprised in this set. Set 3, Groups I, II, III, and IV, mosquitoes Nos. 7, 8, 9, 10, 11, 12, 13, and 14. Mother mosquito.—The mother mosqhito of this set was one of a number of Stegomyia Poacuate raised from larve in our laboratory @On Oct. 8, 10, and 12, it was permitted to fill itself by stinging an immune. After Oct. 16, fed with sirup. >We mention only the mosquitoes that survived and were used for inoculation; others, including males, are ignored in this report. : ¢On Oct. 6, 8, 10, 12, and 15, fed by stinging an immune. After Oct. 16, fed with sirup. 110 and, without any prior feeding, was made to sting on October 4, at 9 a. m., a severe case of yellow fever (Melancon) 30 hours after the initial chill.¢ Group I.—October 18, at 4.20 p. m. (14 days after the feed of yel- low fever blood), this insect deposited some eggs, from which there was hatched November 12, at 9 a. m., an adult female Stegomyia fusciata, which formed Group I of this set and was given the num- ber.6. Group I[.—October 19, at 4.30 p. m. (15 days after the feed of vel- low fever blood), this mother mosquito laid another batch of eggs, from which there were hatched between November 7 (8.30 a. m.) and November 9 (8.30 a. m.) three female Stegomyia fasciata, numbered 7, 8, and 9, which form Group II of this set. Group I[I.—November 12, at 9 a. m., there was hatched an addi- tional adult female Stegomyia fasciata, which was numbered 10 and forms Group III of this set. ° Group IV.—Between November 13 (8.30 a. m.) and November 18 (8.30 a. m.) there were hatched four additional females, numbered 11, 12, 13, and 14, which comprise Group IV of this set. At stated intervals these fourteen Stegomyia fasciata, the progeny of mothers (Sets 1, 2, and 3) that had fed on cases of yellow fever as above indicated, were made to sting nonimmune subjects, and during the intervals fed upon sirup. Mosquitoes Nos. 1 and 2 (Set 1, Group I) were applied to and stung seven nonimmunes (A, B, C, D, G, H, K) at various invtervals between the sixth and thirty-ninth day after completing their meta- morphoses, as shown in Table 2. TaBLE 2.—Inoculation with mosquitoes Nos. 1 and 2. {Nonimmunes are designated by capital letters.] Stung Age of Stung Age of Mosquito. nonim- | Mosquito Mosquito. nonim- | Mosquito muue. | at time of a mune. | at time of stinging. stinging. Days. 20-21 24-25 OQPamyr AMaow re e wo Of these inoculations, four were made after the twenty-second day (the mosquito incubation period in the successful case reported by Marchoux and Simond), namely, at age periods of 24, 32, 35, and 39 days.. 4On Oct. 6, 8, 10, 12, and 14, fed by stinging immune. After Oct. 15, fed with sirup. 111 - Mosquitoes Nos. 3 and 4 (Set 1, Group II) were made to sting eight nonimmune subjects (B, E, F, G, J, L, M, and N) ten times at inter- vals between the thirteenth and forty-ninth day after emergence as adult insects, as shown in Table 3. TaBeE 3.— Inoculation with mosquitoes Nos. 3 and 4. [Nonimmunes are designated by capital letters.] | Age of Age of Stung . Stung * Mosquito. nonim- | Mosquito Mosquito. nonim- | Mosquito , mune— | 2t time of mune— | 2t,time of stinging. || . stinging. Days. Days. Nos.3 and 4 B 13-14 J 83-34 No.3. E 21-22 aL 37-38 No.4 E 23-24 M 42-43 No.3... “ F 26-27 G 45-46 Nos.3 and 4......-.......--- a 29-30 N 49-80 aSubject. passed from observation at the end of 5 days, Mosquito No. 5 (Set 2) was made to sting subject F on two separate days; the first time 25 and the second 27 days after reaching the adult stage, 3 and 5 days, respectively, later than in the positive case reported by the French workers as shown in Table 4. TaBLe 4.—Inoculations with mosquito No. 5. [Nonimmune is designated by a capital letter.] Age of Age of Stung i Stung ; Mosquito. nonim- aay Mosquito. nonim- ae mune— JUS 0: mune | #t.timeo stinging. stinging. Days. ||" ; Days. F 25-27 || NOB iinsescce oe tow seice nem F 27-29 Mosquito No. 6 (Set 8, Group I) was made to sting at age periods of 2, 4, 6, 9, and 12 days longer than in the successful case reported by ‘Marchoux and Simond. In all, five subjects were used. Taste 5.—Inoculation with mosquito No. 6. * [Nonimmunes are designated by capital letters.] Age of Age of Stung <4. | Stung Mosquito. nonim- | Mosquito Mosquito. nonim- | Mosquito mune— | 2t.timeo: mune— | t time o stinging. stinging. Days. « Days. F 24 || NOs Gxcoseexssensmseemeesees J 31 G 2G || INO: Gin siciain niniSinins ate pistecenae se M 34 H 28 Mosquitoes Nos. 7, 8, and 9 (Set 3, Group II) were made to sting subjects Band F. Subject B was stung by all three insects 3 (to 5) days after completing their metamorphoses. Subject F was stung by e 112 insect No. 9 on the twenty-fifth (to twenty-seventh) and again on the twenty-seventh (to twenty-ninth) day after its metamorphosis. Taste 6.—Inoculation with mosquitoes Nos. 7, 8, and 9. ({Nonimmunes are designated by capital letters.] Age of Age of Stun * Stung . Mosquito. Bona mosquito Mosquito. nonim- POs ULG, : at time of mune— | #t,time o: mune stinging. r stinging. Days. Days. Nos. 7, 8, and 9..........2.. B 825). MING Diaseeetnacpcterlneiaaretotme F 27-29 NOs 9 pereeieectedanaseie tens F 25-27 Mosquito No. 10 (Set 3, Group II) stung subjects B and G, 2 and 26 days respectively after emergence from the pupal shell, the latter inoculation being 4 days after the 22-day period. TaBLe 7.—Inoculation with mosquito No. 10. [Nonimmunes are designated by capital letters.] Age of Age of Stung * Stung * Mosquito. nonim- mosquito, Mosquito. nonim- a mune— | 8¥.¥me o mune— | #t time o stinging. stinging. Days. Days. NOM Otxcaess ones eee eceeadey B PN NO 0s cccsasworasicnctcmeee G 26 With mosquitoes Nos. 11, 12, 18, and 14 we made one inoculation at least 22 days after completing their metamorphoses, and nine inocula- tions of seven subjects (B, F, G, J, L, M, and N) at varying intervals, after this period up to and including the fortieth day after attaining the adult stage, as shown in Table 8. TaBLE 8.—Inoculation with mosquitoes Nos. 11, 12, 18, and 14. [Nonimmunes are designated by capital letters.] Age of Age of Stung Stun és Mosquito. nonim- Payee Mosquito. tontui- presi mune— | ‘stinging. mune— | ‘stinging. Days. Days. H 22-27 || NOD eeeecten seas ssreceseees, F 82-37 J 23-28) || NOS aera sinnaas sere B 82-37 J 25-30 || Nos, 12, 18,and 14 G 34-39 G 25-80 ||" Nos, 12 and 13......... J 36-41 aL 26-31 || Nos. 13 and 14......... aie N 39-44 oM 80-89. || NO. 1Qis. cecnscasennaecniccme N 40-45 aSubject passed from observation after 6 days. >Subject passed from observation after 5 days. We have recorded above our work with particular reference to the mosquitoes. Below (Table 9) we tabulate it with reference to the non- immunes who were the subjects of the inoculations. 118 TaBLe 9.—Nonimmunes and inoculations to which they were subjected. Age of mos- Subject, age, and nationality. Stung by mosquito— wae a loculation.a : Days. A, nonimmune, 23 years, Canadian........ abe fokecaeemaweranse a B, nonimmune, 44 years, Dalmatian................-.eeeeeee eee Nos. 6 and 10.....-.... 2 4 Nos. ae 8, and 9....... 3 e NOG 1. aie asian sincicoare's 9 Nos. 8 and 4.......... 13 Nos. land 2.........- 20 NOP? sicescsnpeweeces 32 C, nonimmune, 16 years, Austrian..........2.-..ceneeeeeeee neon NO) 2 ied Sesisetarceies aus 10 : Nos. 1 and Dito stcataeis| 18 D, nonimmune, 26 years, Norwegian.......--..........22 eee eee Nos. land 2.......... 24 Eg nonimmune, 21 years, American... 21 F nonimmune, 23 years, American Bi 26 27 32 G, nonimmune, 23 years, American a 29 No. 32 Nos. 12, 13, and 14 34 H, nonimmune, 34 years, American..........--2---+eeee eee e eee eae ll'and 12... a ;. 0.0.....----- NO 52 secisroretorciziere 35 J, nonimmune, 45 years, Irish... .......2-.. see eee eee eee e eee eens Nos. 13 and 14 23 : : 3 Nos. 1l.and 12 ........ 25 pene Siete eseeaet ees 31 so wielareicninigeesisibia ates 33 Nos. 12and 13....-... 36 K, nonimmune, 27 years, Norwegian............-.--+--eeeeeee eee NOs 2) ecieis cesistiaqscceccs, 39 L, nonimmune, 38 years, American No. 14 a M, nonimmune, 20 years, American a N, nonimmune, 31 years, Irish.........-.. Diuin ewe weet erasawieve: 39 No. 12 oe 7 : a Ages given in this table are minimal. For further details consult previous tables. In all, thirteen subjects were used. After each inoculation they were kept under observation for at least 7 days, except in three instances, in two of which the observation period was 5 and in the third 6 days. Our results were uniformly negative, no reaction of any kind being observed in any of the subjects of our inoculations. . CONCLUSION. In view of the negative results recorded by us in our efforts to con- firm the positive work of Marchoux and Simond, we feel that addi- tional work will be necessary to settle the question of the hereditary transmission of the parasite of yellow fever in the Stegomyia fasciata. Nevertheless, the sanitarian will do well to continue his measures of mosquito destruction after the suppression of an epidemic. & APPENDIX.? THE HEREDITARY TRANSMISSION OF THE VIRUS OF YELLOW FEVER IN THE STEGOMYIA FASCIATA. By E. Marcuovux and P. L. Srionp. ‘Among the new facts concerning yellow fever which we gathered in Brazil there is one the importance of which obliges us to publish at once. It concerns the question of the possibility of the hereditary transmission of the yellow fever virus from mosquito to mosquito. . Since 1903 our attention has been turned to the fact that in certain foci of an epidemic zone it is at times difficult to find a case of yellow fever of recent date as the origin of the new cases which spring up at a given time. There being no doubt that the lighting up of these foci was due to the presence of infected Stegomyia fasciata, we were forced to conclude that one or several of these mosquitoes had in some way been imported from a distant point where the disease existed from which they had drawn the virus. This undoubtedly occurs frequently. We, nevertheless, were led to ask ourselves if, under certain circum- stances, eggs derived from a Stegomyia infected in the course of an epidemic some months prior to the one observed could not have given birth to Stegomyias hereditarily infected. Several experiments were made in 1903 to confirm this hypothesis. We had some Stegomyias lay eggs that had stung some cases early in the disease. -The eggs were hatched into larve, and the adult insect raised from these was made to sting a human subject. These experiments did not give us positive results at that time, although the subjects that had been bitten by these mosquitoes were not immune to the disease, for subsequently it was possible to give it to them by injections of fresh virulent serum. We resumed these experiments in February, 1905. We collected a number of eggs of one laying from a Stegomyia 20 days old which had stung several of our cases in order to determinea heavy infection, and the larvee which were hatched the 4th of February were placed in a jar to be reared. The adult insects began to emerge February 16. These, isolated in tubes from the time of emergence, were fed with «Translated from Comptes Rendus, Société Biologie, Paris, Vol. LIX, No. 27. August 4, 1905, p. 259. (114) 71SEC "PRESEN 115 sirup until March 2. At this date, 14 days after the metaniorphosis, two of these Stegomyia stung subject A, a Portuguese, who had arrived in Brazil a few days before, and had up to that time never had yellow fever. The subject showed no reaction following this inoculation. He was stung again by one of these two mosquitoes (the second having died in the meantime) on the 10th of March, 8 days after the first inoculation. Four days later, March 14, he developed a typical though mild attack of yellow fever. The character of the period of invasion, the vomiting, the pains, the course of the temperature, the icterus, and the progress of convalescence permitted no doubt as to the nature of the disease. We deemed it a duty, nevertheless, to confirm our diagnosis experi- mentally. After recovering, this subject was twice submitted to the stings of several Stegomyia infected by a case of yellow fever. He showed himself absolutely refractory to these inoculations, as do all individuals recently immunized by a first attack. Let us add that the conditions under which he was observed by us - from the time of his arrival in Brazil do not permit that any source of contamination, other than the hereditarily infected mosquito by which he had been stung, could have brought on the attack of yellow fever which he had presented. It may be concluded from this experiment that under conditions. which can not as yet be precisely defined the Stegomyza fasciata, the. progeny of a mother directly infected by a case of yellow fever, are ‘themselves infected hereditarily. It follows from the various experi- ments done on this subject that the time needed by the mosquito hered- itarily infected to become capable of discharging the virus with its salivary secretion is longer than in the case of the mosquito which has, drawn the virus directly from the blood of a patient. This period was 22 days in the positive case. It follows likewise, both from experiments and from epidemiologic facts, that this hereditary transmission can not be considered as the. general rule but rather as an exceptional occurrence. The mildness of the attack suffered by A warrants the belief that the passage of the virus from one generation of Stegomyia to another is accompanied by a certain amount of attenuation. This may bea new field open to research with reference to vaccination against yellow fever. The knowledge of this mode of propagation explains one of the most obscure points in the history of yellow fever, that of the recur- rence of certain epidemics under conditions where a primary case can not be found that is sufficiently recent to explain the infection of the Stegomyia. Finally, its importance can not be disregarded from the point of view of prophylaxis. O YELLOW FEYER, INSTITUTE, BULLETIN No, 16 0 iblid. Health and Marine Hospital Benton: Surgeon General YELLOW _ETIQ janie SYMPTOMS ~* JOSEPH GOLDBERGER JULY, 1007 WASHINGTON — GOVERNMENT PE ive ao a 9 YELLOW FEVER INSTITUTE, BULLETIN No. 16 Treasury Department, U. 8. Public Health and Marine- Hospital Service WALTER WYMAN, Surgeon-General e YELLOW FEVER ETIOLOGY, SYMPTOMS AND DIAGNOSIS BY JOSEPH GOLDBERGER JULY, 1907 WASHINGTON GOVERNMENT PRINTING OFFICE 1907 YELLOW FEVER AINSTITUTE. Treasury Department, Bureau of Public Health and Marine-Hospital Service. WALTER WYMAN, Surgeon-General. Buiwetin No. 16. YELLOW FEVER. ETIOLOGY, SYMPTOMS AND DIAGNOSIS. By JoszrH GotpBERGER, Passed Assistant Surgeon, U. S. Public Health and Marine-Hospital Service. _ ETIOLOGY. The claims, by various authors up to 1890, of having discovered the specific cause of yellow fever, were all effectually disposed of by the investigations of Sternberg. Since that time several investigators -have reported finding the specific causative agent; but it is notable that no two of the micro-organisms for which this claim was made were identical, and since only one could be the specific organism, it is evident that the others could have no real claim to specificity. Of the organisms referred to, that described by Sanarelli (1897) as the Bacillus tcteroides attracted most attention and, indeed, was at first: hailed as the long-looked-for germ. A series“ of epoch-making investigations and discoveries by a com- mission composed of Walter Reed, James Carroll, Aristides Agra- monte, and Jesse W. Lazear, medical officers of the United States Army, which have been fully confirmed and in some respects amplified by independent workers—Cuban?, Brazilian’, American’, French?®, German /—have resulted in establishing: 1. That yellow fever is transmitted, under natural conditions, only by the bite of a mosquito (Stegomyia calopus) that at least 12 days Reed, Carroll, Agramonte, and Lazear, 1900; Reed, Carroll, and Agramonte, 1901a, and 1901b; Reed and Carroll, 1902. > Guiteras, 1901. ¢ Barreto, de Barros, and Rodrigues, 1903. 4 Ross, 1902; Parker, Beyer, and Pothier, 1903; Rosenau, Parker, Francis, and Beyer, 1904; Rosenau and Goldberger, 1906. ¢Marchoux, Salimbeni, and Simond, 1903; Marchoux and Simond, 1906a, 1906b, 1906c. f Otto and Neumann, 1905. (3) 4 before has fed on the blood of a person sick with this disease during the first 3 days of his illness. » 2. That yellow fever can be produced under artificial conditions by the subcutaneous injection of blood taken from the general circu- lation of a person sick with this disease during the first 3 days of his illness. _ 8. That yellow fever is not conveyed by fomites. 4, That the Bacillus icteroides Sanarelli stands in no causative relation to yellow fever. As all preventive measures are based on the foregoing fundamental propositions, a somewhat more detailed consideration of each is desirable. A.— Yellow fever is transmitted, under natural conditions, only by the bite of a mosquito (Stegomyia calopus) that at least 12 days before has fed on the blood of a person sick with this disease during the first three days of his illness. The unusual prevalence of insects during some epidemics of yellow fever was noted more than a century ago. It was not until 1848, however, that any suggestion was made as to their etiological con- nection. In that year Josiah C. Nott of Mobile, Ala., reasoning from certain epidemic peculiarities of the disease, expressed it as ‘‘ probable that yellow fever is caused by an insect or animalcule bred on the ground,” and mentioned “‘‘mosquitoes, flying ants, many of the aphides” as illustrations of insects whose general habits were such as to fulfill the requirements as transmitters of the diseage. At about this time there appears to have prevailed a fairly widespread belief in the existence of some relation between mosquitoes and yellow fever, for Dowler, writing in 1855, states that many persons regarded ‘‘any increase in the number of mosquitoes as a’certain prelude or precursor to a yellow-fever epidemic.” The first to definitely assert that the mosquito is the medium of trans- mission and to specifically indicate the mosquito concerned was Carlos J. Finlay. In 1881, at a meeting of the Royal Academy of Medical and Physical Sciences of Habana, he stated that three conditions were necessary for the propagation of yellow fever, namely: ‘‘(1) The existence of a yellow fever patient into whose capillaries the mosquito is able to drive its sting and to impregnate it with the virulent parti- cles, at an appropriate stage of the disease. (2) That the life of the mosquito be spared after its bite upon the patient until it has a chance of biting the person in whom the disease is to be reproduced. (3) The coincidence that some of the persons whom the same mosquito hap- pens to bite thereafter shall be susceptible of contracting the disease.” During the succeeding twenty years Finlay continued, tenaciously, to 5 maintain his theory which, in collaboration with Delgado, he attempted, though unsuccessfully, to prove. To Reed, Carroll, Agramonte, and Lazear is due the credit for the masterly experiments which converted a discredited hypothesis into an established doctrine. The transmission of the disease by the mosquito is not, as Finlay thought, a simple mechanical transfer from one individual to another, such as occurs at times in plague through the instrumentality of fleas or in surra through biting flies. In these diseases neither the flea nor the fly is necessary, but in yellow fever not only is the mosquito nec- essary, but it is essential that the mosquito be of a particular species or at least of a particular genus. Thus, attempts to transmit the disease by means of mosquitoes of other than the genus Stegomyia® have not been successful. It has been found, furthermore, that in yellow fever, unlike either surra or sleeping sickness, a certain period must elapse after the infect- ing feed before the mosquito is capable of communicating the disease.? Experimentally this interval appears to be not less than 12¢ days, so . that a susceptible individual may expose himself with impunity. to repeated stings within the first 10 or (?) 11 days @ after the mosquito has fed on a person sick with the disease. This is the period of ‘extrinsic incubation” of Carter, whose painstaking observations at Orwood and Taylor, Miss., in 1898, resulted in his tentatively fixing this interval as “‘ usually in excess of 10 days” and served, in the light of the then recent discovery of the mosquito transmission of malaria, to direct the attention of the Army Commission to Finlay’s mosquito as a possible ‘‘ intermediary host” for this disease. The duration of this period of ‘‘ extrinsic incubation” is decidedly influenced by the temperature of the air. It is at its minimum at temperatures above 26° C (80° F), but becomes progressively longer as the temperature declines below this point. The period of the disease at which the mosquito bites is another essential factor in the latter’s power to transmit the disease. Thus all attempts to produce an attack by means of the bites of mosqui- toes that had previously fed on cases after the third day of the @No experiments have as yet been recorded with any species of this genus other than S. calopus. 6In surra and sleeping sickness for example, no such interval exists. On the contrary, it is only during the two days immediately following the infecting feed that the tsetse flies concerned can transmit these diseases. After the third day their bite is perfectly harmless. In dengue this interval appears likewise to be absent. ¢I say ‘‘appears to be,’’ because the recorded experimental evidence,is not suffi- cient to prove that it may not under favorable conditions be a (very) little shorter than 12 days. @Nor do such bites during this period confer, as Finlay believed; an immunity from subsequent attack. 6 ‘ disease have failed,* whereas all successful attempts have been with such mosquitoes as had been allowed to feed on cases during the first three days. There are some who, while granting that the mosquito is capable of transmitting the disease directly by biting, maintain that the disease may also be acquired by ingesting water in which the body of an infected mosquito has disintegrated. Again, there are others who, while admitting that the mosquito is the sole medium of transmission, hold, nevertheless, that there may be sources other than the one men- tioned from which this insect may acquire its infection, and suggest black vomit or articles soiled by yellow-fever patients as pertinent illus- trations. But neither the results of experiments especially designed to test these hypotheses nor the indirect evidence furnished by a large mass of observations give the slightest support to these assumptions. After the mosquito has become infective it probably remains so for life. B.— Yellow fever can be produced under artificial conditions by the * subcutaneous injection of blood taken from the general circulation of a person sick with this disease during the first 3 days of his illness. The subcutaneous injection of a drop? (0.1 cc.) of yellow fever blood serum from a case in the first day of illness has produced an attack of yellow fever, whereas five times this amount from a case in the fourth day of the disease produced no symptoms. C.— Yellow fever is not conveyed by fomites. Before the demonstration by the Army Commission of the trans- mission of yellow fever through the mosquito it was very generally believed, notwithstanding a large mass of evidence to the contrary, that the disease was communicated by the exhalations of. the sick, by contact with their excretions, or with articles that had been exposed to or been soiled by them. In order to put this almost universal belief in fomites to a rigorous test, the Army Commission exposed each of a series of seven non- immunes to clothing and bedding which had been used by cases of yellow fever and which had become soiled with blood, urine, feces, and black vomit. The house in which the experiment was carried out was especially constructed for the purpose in an isolated place near Habana. In order to prevent access of mosquitos and to simu- @The recorded experimental evidence is not sufficient to show that this infective period may.not at times extend into the fourth day. This is of considerable prac- tical importance. A case of yellow fever should be protected from mosquitoes during four full days at least. bParker, Beyer, and Pothier (1903) induced an attack of yellow fever by the sub- cutaneous injection of 0.033 cc. of filtered serum from a case in the third day. 7 late the conditions thought most favorable to infection by fomites, the windows and doors were screened and so placed as to prevent free ventilation, special pains were taken to exclude sunlight, and pro- vision was made for heating during the day so that an average temperature of 72.6° F. was maintained throughout the entire period. The men were exposed in squads for periods averaging 21 nights each. Each ‘squad ‘entered the house at night, removed the soiled articles from the boxes in which they were packed, shook them out, hung some about the room, and used some for making up the beds in which they slept. In the morning the various garments and articles of bedding were repacked and the men left the room to occupy a near-by tent during the day. The result of this experiment was entirely negative; the men remained in perfect health. Subsequently some of them submitted to mosquito inoculation and promptly sickened with the disease, showing conclusively that they were not. immune. It may be of interest to observe that the first experiments to deter- mine the infective power of fomites were made over a century ago. In 1800 Cathrall reported having repeatedly applied black vomit to his tongue and lips and to the skin of various parts of the body with- out experiencing any ill effects. In company with a friend he had, besides, exposed himself to the fumes of heated black vomit, both in the open air and in a confined space, likewise without harm. In 1804 Ffirth, imitating Cathrall’s example, went so far as to repeatedly swal- low several ounces of fresh black vomit; he rubbed some into incisions in his arms and dropped some into his eye without experiencing any but momentary disagreeable effects. In view of the foregoing, one can not but admire the acute reason- ing of La Roche,* who, half a century ago, in discussing the evidence in, support of transmission through the agency of clothes, bedding, merchandise, etc., concluded that “‘we may well infer” that in the record of such instances ‘‘some error has crept"in—something has been omitted or overlooked—and that the production. of the disease was really due to some other agency than the one contended for,” a con- clusion which will be concurred in by anyone who will take the pains to critically examine the recorded instances of alleged transmission by such means. D.—Eaperiments to show that the Bacillus icteroides Sanarelli stands in no causative relation to yellow fever. The fact that the Army Commission was able to produce three cases of yellow fever by the subcutaneous injection of blood which was shown to be sterile by the culture method is sufficient to eliminate Vol. 2, p. 522, 8 B. icteroides from consideration. That the attacks of fever so produced were not simply such as might be caused by the injection of a soluble toxine circulating in the blood is shown by the following chain of experiments: . The first link in the chain was a fatal nonexperimental case of yellow fever which furnished the Army Commission® with blood that culturally showed the absence of B. zcterocdes, but 0.5 ce. of which injected subcutaneously into a nonimmune (W. F.)¢ induced an attack of fever having all the characters of yellow fever. From the latter case blood was drawn and 1 cc. injected into a second nonimmune (J. H. A.)¢; culturally this blood was sterile, but nevertheless it caused an attack in all respects similar to yellow fever. ight hours after the onset of this man’s illness some mosquitoes were allowed to bite him, one of which, 26 days later, was applied to a nonimmune (Vergara) °, who developed an attack of yellow fever 3 days, 10 hours later (see diagram). Diagram. Non- First. * Second. Third. experimental Experimental Experimental Experimental case. a case. case. case. Induced by injection of Induced by injection Induced by bite 0.5 cc. blood from No.1. of 1 ec. blood from No. of a‘ mosquito that Cultures from blood, no 2. Blood cultures ster- had fed on No. 3, B. icteroides. ile. 26 days before. The only possible explanation of this chain of events is that there was present in the blood used for the subcutaneous injections an organism that can not be cultivated on ordinary media—B. icteroides grows readily on all ordinary media—and that the mosquito that bit the second of the experimental cases became infected with this organ- ism and 26 days later transmitted this infection to a nonimmune. It is inconceivable that a toxine alone could infect a mosquito in such a way as to enable the latter, 26 days later, to reproduce the disease by biting a nonimmune. ‘It may be observed in this connection that a person who has suffered from an attack of the disease, acquired natu- rally or experimentally through the bite of a mosquito, is immune to injections of virulent yellow fever blood serum and, vice versa, an attack of the disease induced by the injection of yellow fever blood protects against subsequent inoculation by means of infected mosquitoes. The parasite.—W hile the organism of yellow fever has not yet been discovered, we are, nevertheless, in possession of some facts which enable us to form some idea of its character. The disease has been found to occur in nature only in man and the mosquito, so that it is @ Reed, Carroll, and Agramonte, 1901b, p. 16. > Guiteras, 1901, p. 812. 9 inferred that the parasite is one of those that requires for the complete evolution of its life cycle a mammalian and an arthropod host. We have familiar analogies in Piroplasma bigeminum of Texas fever and the Plasmodium of malaria. Because of these analogies it is inferred that biologically it may be grouped with them as a protozoon. On the basis of these and other analogies, both Schaudinn (1904) and Novy & Knapp (1906) have suggested that it may be a Spirocheta. Stim- son’s recent discovery of a spirocheete-like organism in the tubules of a yellow fever kidney is, therefore, exceedingly interesting and suggestive. The cycle in man is represented clinically by a stage of incubation and by a stage of fever. Some attempts to infect mosquitoes by allow- ing them to bite subjects during the stage of incubation, in one instance as late as 6 hours before the onset of the stage of fever, have been unsuccessful; whereas a mosquito that bit a case of the disease 8 hours after the onset became infected and conveyed the disease to a nonimmune 26 days later. This would indicate that the parasite does not appear in the circulating blood until the onset of the disease. We already know that it remains in the blood only during the first three days of the disease or, at least, it is only during those three days that it exists in a form capable of continuing its life cycle in the mosquito or ina fresh nonimmune. : In the circulation it exists in a form so minute as to be capable of passing through the finest grained porcelain filters, such as the Cham- berland B and the Chamberland F. Its resistance to deleterious influences is feeble when withdrawn from the circulation. When kept in a test tube exposed to the air in the dark, at a temperature of 24° C. (75° F.) to 30° C. (80° F.), it loses its virulence in 48 hours. Under the same conditions, but pro- tected from the air by keeping under oil, it retains its vitality some- what longer—up to between 5 and 8 days. Heating for 5 minutes at 55° C. (182° F.) apparently suffices to kill it. The etfect of low temperatures has not been studied. The cycle in the mosquito requires at least 12 (?) days* for its com- pletion. As to the changes which it undergoes during this period we are in complete ignorance. The French commission has recorded one experiment which would indicate that the parasite may, under certain circumstances, be trans- mitted to the progeny of an infected mosquito through the egg. An attempt by Rosenau and Goldberger to confirm this resulted negatively. The same commission attempted, but without success, to transmit the parasite from one mosquito to another by feeding larve with cadavers of infected adults; they appear, however, to have supeecded in trans- @See page 5, footnote ¢, 2742—No, 16—07——2 10 mitting the parasite to a mosquito by feeding it with sirup in which the body of an infected insect had been crushed. Judging from the variations in the virulence of different epidemics it is fair to infer that there is a corresponding variation in the viru- lence of the parasite. The variation in severity of individual cases appears, however, to be largely influenced by the susceptibility or resistance of the subject, for the bite of the same mosquito or mos- quitoes will be followed in one instance by a severe and in another by a mild attack. Nor does there appear to be any appreciable difference in severity between attacks induced by the bite of a single as com- pared with those induced by the bites of several insects. Susceptibility.— Attempts to induce the disease in the ordinary lab- oratory animals have been unsuccessful. Marchoux and Simond (1906a) caused a mild febrile attack in one orang-outang and in one chimpan- zee by bites of infected mosquitoes. Thomas (1907) induced a mild febrile attack with albuminuria in a chimpanzee rellowing an inocula- tion by infected mosquitoes. All persons are naturally susceptible, but there is a difference in the degree of this susceptibility in different races. Thus the mortality in the negro is less than in the Caucasian. Age has a distinct influence on susceptibility, as is shown by the mildness of attack and relatively low mortality in children. Nativity and long-continued residence in an endemic focus were supposed at one time to ‘‘acclimatize” and thus protect against the disease, but it is now believed that this protection was obtained not by the occult influence of climate but by having had during childhood or at some other age a mild and unrecognized attack of the disease. THE YELLOW FEVER MOSQUITO. This insect has been known by a variety of names of which Culex mosquito, Culex teniatus, and Culex fasciatus were in most common use up to 1901. In that year Theobald, having observed that some sixteen species of Culex, while agreeing amongst themselves, differed from the others of this genus in certain peculiarities of scale arrange- ment, separated these into a group to which he applied the name Stegomyia. In this group was included the yellow-fever mosquito whose name thereupon became Stegomyia fasciata. Blanchard (1905), however, has pointed out that the specific designation fusciata is not applicable to this insect, as it had first been applied to another, so that calopus, suggested by Meigen in 1818, has the right of priority. There- fore, under the rules of zoological nomenclature, the correct name is Stegomyia calopus (Meigen, 1818) Blanchard, 1905. Adult.—The Stegomyia calopus (figs. 1 and 2) is readily recognized. It isa handsome insect—a study in black and white. The distinction MESONOTUM, oa eer petro.t or 1 SuBmaRoinar CELL SCUTPLLUM. _.. METATHORAY 0... essen HALTERE *= <1 220-2 --+o-fe at a <> TTT ABDOMINAL SEGMENTS Fic. 1.—External anatomy of Stegomyia calopus. Fic. 2.—Stegomyia calopus (female). 11 tween the male and the female is readily discernible in the characters the antennx; in the former (fig. 3) these organs are prominent and ithery— decidedly hirsute. Another prominent point of difference ists in the length of the palpi; in the male they are long—almost as ig as the proboscis, but in the female they are short—less than one- rd the length of the proboscis. The palpi in both sexes are black, but are ornamented with white iles which, in the male, are arranged as four narrow bands, while in e female they are collected into a white tuft at the tip. The proboscis is black and is devoid of ornamentation, differing in is respect from both Culex twniorhynchus and Culex sollicitans, ch of which has the proboscis marked by a pale band in the middle. 1ese two insects bear a superficial resemblance to S. calopus, for rich they are not inffequently istaken by the uninformed. The head is clothed by the broad it scales characteristic of the mus. These scales are black, ex- pt for a line of white down the iddle extending to the neck and narrow white border to the eyes. The thorax is dark brown, almost ack, ornamented with silvery hite patches and lines of which ie following are peculiar to and stinctive of this species, and en- dle one to recognize it at a glance: _well marked, easily recognizable, ure white curved line on either yg. 3 appendages of head of Stegomyia de of the back (mesonotum) be- _ ealopus (male). veen which, but less obvious to the naked eye, are two delicate tedian parallel lines; a prominent transverse white line of scales o the scutellum. The abdomen is clothed with black and white scales, the latter col- ted in bands at the bases of the abdominal segments, and in distinct atches at the sides. . The legs are black scaled, except for white bands which are arranged ; follows: A basal band on the first joint of the fore, on the first and xcond of the mid, and on all of the hind tarsi except the last, which as a rule, all white. Each leg is provided with a pair of claws hich are equal in size in the female but unequal in the male. They iffer in other respects in the two sexes; in the female those of the fore ad of the mid legs are provided with one tooth, those of the hind .gs are simple; in the male all the claws are simple except the larger ne of the forefoot. 12 The veins of the wings are clothed with dark brown scales. The first submarginal cell is longer than the second posterior cell and the base of the former is nearer the root of the wing. Biting.—The male insect does not bite; it lives almost exclusively on vegetable and fruit juices. In the females, however, a feed of blood is a necessary condition precedent to egg laying. At summer temperatures this insect will digest a full meal of blood in about 48 hours. If disturbed in the act of feeding it will fly away, but will return and attempt to finish its interrupted meal. In this way one infected mosquito in its efforts to obtain one full meal may bite several individuals, and so may, almost simultaneously, produce more than one case of yellow fever. It. has long been observed that communication with an infected town is distinctly safer during the day than after dark. In an effort to explain this phenomenon the French yellow fever commission first suggested, then made some experiments which appear to show that under natural conditions the yellow fever mosquito, after the first week, ceases to bite during the day and bites only at night—that is, between 5 p.m.and 7a. m. These results are not, however, alto- gether in harmony with the observations of others, and there are cases recorded showing that yellow fever may be contracted by visit- ing an infected house during theday.?_ We must conclude, therefore, that the Stegomyia calopus, young or old, may bite at any time dur- ing the 24 hours, though probably it is most vicious about dusk and about dawn. The female is impregnated almost immediately after her birth, and then proceeds to seek a blood feed; 3 or 4 days after this she is ready to lay her eggs. Breeding places.—The Stegomyta calopus appears to be strictly a house mosquito—a domestic though not domesticated animal. Her breeding places, therefore, may be expected, and actually have been found to be any collections of water in and about habitations, such as cisterns, wells, water barrels, tubs or jars with or without water plants, sagging roof gutters, more or less broken and discarded crockery, bottles and tins, fountains (not containing fish), cemetery vases, baptismal’ and other fonts in churches, chicken or horse troughs, grindstone troughs, and tubs or barrels containing water which has been softened and made more or less alkaline by the use of ashes. The larve have been found in tin cans containing fecal matter, in cesspools, and in some natural collections of water formed by leaves of certain tropical plants, such as the palm and century plant. Ordi- narily, she does not seek street puddles or gutters, favorite breeding places for Culex teniorhynchus and Culex pipiens (=pungens), though her larve have been found in these situations. 4 Carter, 1901b, p. 936. 13 £gg.—The female lays her eggs (fig. 4) on the surface of the water or on the sides of the container at or just above the water line. The eggs do not adhere one to the other to form the compact boat-shaped masses characteristic of Culex (fig. 5), but lie on their sides more or less isolated, though frequently grouped into clumps. At the moment of laying the eggs are of a cream color but rapidly become jet black; they are somewhat cigar shaped with one end slightly broader and more bluntly rounded than the other. They measure on an aver- gm age about 0.55 mm. in length and «~ fF 0.16 mm. in width at the broadest &! part. Under the microscope the gy apparently cylindrical egg is seen to be slightly flattened” on one side. The eggs are most commonly laid during the night or early morning, but they may be laid at any time during the 24 hours. The total number of eggs laid varies, the average being about 65 to 70; the maximum recorded is 144.“ The act of ovipositing appears to greatly exhaust the mosquito, so that it may fall on the surface of the water and die immediately after even the first egg laying. There are numerous exceptions, however, andthe act may: be re- peated several times and the mosquito survive for some time after. If laid on the surface of the water the egg floats, being supported by the Fic. 5.—Eggraft and eggs of Culex (after Stephens & surface film. Disturbance Christopher, 1904). of the water surface may cause the egg to become wet and sink to the bottom, but this does not prevent its hatching out into the larva. The egg shows marked powers of resistance to unfavorable influences. Thus it may be kept dry for from two or three to six and one-half months? and still retain its . vitality and hatch out when put back into the water. Reed and Carroll ¢ have shown that freezing does not destroy its vitality. The egg probably plays the leading réle in the hibernation of this mosquito. Under the most favorable conditions as to temperature (30° C. (86° F.) and over) eggs hatch out in about 36 hours after they are laid, but with a lowering of the temperature this period becomes progress- ively longer until 20° C. (68° F.) is reached, below which they will not hatch at all. Fia. 4.—Eggs of Stegomyia calopus (after Stephens & Christopher, 1904); @Marchoux and Simond, 1906b. %Francis, 1907. ¢ Reed and Carroll, 1901. 14 Larva.—The egg hatches into the larva (‘‘ wiggle-tail”) (fig. 6), which can be distinguished readily from the larva of Culex pipiens RESR SIPHON Fia. 6.—Larva of Stegomyia calopus (after é Howard, 1901). surface for air. It thrusts its breath- (fig. 7), its most common messmate, by the color and proportions of the breath- ing siphon (air tube). Inthe S. calopus the respiratory siphon is black and somewhat barrel-shaped, with its great- est transverse diameter equal to about one-half of the length; whereas in Culex pipiens the air tube is brown, longer, more slender, and with the greatest transverse diameter less than one-third of the length of the tube. The larva, though it lives in the water, is strictly an air breather and must come to the ing tube up into the surface film and remains suspended head down, at an angle somewhat less than 45°, for a variable time. A film of oil on the sur- face of the water is sufficient to obstruct- the air tube, and thus cause the death of the larva by suffocation. The larva is very timid, so that a very slight jar or a sudden shadow will cause it to move rapidly to the bottom of the container where, indeed, it may very commonly be observed to feed. Fic. 7+—Larva of Culex pungens (after Howard, 1901). The duration of the larval stage is influenced by food supply and temperature. With an abundant supply of food and under favorable 15 conditions of temperature this stage lasts not less than 6 or 7 days; under conditions where the supply of food is scanty or the tempera- ture reduced the duration of this stage may become very much pro- longed (weeks) or development may altogether cease. In the latter case the larva may die without completing its metamorphosis or, with the return of favorable conditions, it resumes its development. Freez- ing for short periods does not appear to injure it. Pupa.—After several moults the larva changes into the pupa (fig. 8). The pupa is not provided with a mouth and does not feed. It spends its time at the surface of the water for, like the larva, it is an air breather, and is provided with two trumpet-shaped breathing tubes which spring, not from the tail as in the larva, but from the dorsum of the thorax. It moves only when disturbed, and then rather rapidly. and jerkily downwards into the depths. The pupal stage lasts at least - 36 hours, during which time important changes take place in its inter- nal organization preparatory to the emergence of the perfect insect or imago. The pupal, like the larval stage, is normally passed in the water. Berry has shown, however, that the pupa may be spilled on the ground without its metamorphosis being in- terfered with. Under the most favor- able conditions it takes at least 9 days from the time the egg is laid to the appearance of the imago. Longevity.—The length of life of Fic. 8—Pupa of Stegomyia calopus (after the adult, female under natural con- ner ditions probably varies greatly. Experimentally, Guiteras (1904a) succeeded in keeping a presumably infected one alive for 154 days at the fall and winter temperatures of Habana. At summer tempera- tures, deprived of water, it does not usually survive longer than 34 to 4 days, and only very exceptionally 5 days. This fact has a bearing on the possibility of transporting the mosquito in bandboxes or trunks. Its activity, which is greatest at about 30° C. (86° F.), distinctly diminishes as the temperature declines and approaches 20° C. (68° F.). Below the latter point and as the temperature of 15° C. (59° F.) is approximated the insect seeks obscure corners for protection, becomes very sluggish, and can only exceptionally be induced to bite. In a refrigerator at 8° to 10° C. (46.5° to 50° F.) Guiteras (1904a) was able to keep some mosquitoes alive without food or water for 87 days. How much longer they mave have lived it is impossible to say, because the experiment was terminated at the end of this time by some ants that gained access to and destroyed the mosquitoes. A freezing tem- perature kills the mosquito rather quickly. 16 In the influence of variations in temperature on the rate of multi- plication, on the activity and on the duration of life of the mosquito we have a satisfactory explanation of the peculiarities of seasonal prevalence of the disease in endemic foci, of the decline of epidemics with the advent of cool weather, and of their abrupt cessation on the occurrence of a severe frost. The occurrence of cases even after a killing frost is explained by the fact, already mentioned, that the S. calopus is peculiarly a house mosquito, and it is for this reason occasionally able to escape the full rigors of the climate. Aérial conveyance.—On this subject I can do no better than quote Carter (1904), who has given it a great deal of attention. Although direct observations on this problem are few, yet there are certain indi- rect ones bearing, however, entirely on the aérial conveyance of the Stegomyia ‘infected with yellow fever. It is notorious that yellow fever is usually conveyed but a short ways aérially ‘‘across the street’’ or more often ‘‘to the house in the rear,”’ which is about as far as it was expected to be thus conveyed. This represents a distance of about 75 yards. The two longest distances recorded in recent times of aérial conveyance, one of 225 meters (Melier) and one of 76 fathoms—456 feet (the writer )—are entirely exceptional. So much for the distance which the ‘‘infected”’ Stegomyia is conveyed—or, rather, usually conveyed—aérially. On the other hand, it is known that vessels moored in certain districts of the Habana harbor did not develop yellow fever aboard except in those who had been ashore or unless they lay close to other vessels which were infected.. This experi- ment has been made on s0 large a scale, with so many vessels, and for so many years that we must accept as a fact that an infected Stegomyia was not conveyed aérially from the Habana shore to those vessels, or, allowing for errors, was very rarely so conveyed. The distance which had been found safe was something over 200 fathoms—1,200 feet. The prevailing wind was generally slightly on shore, but was not constantly blowing. Whether there is any difference in the distance to which infected or noninfected mosquitoes are conveyed is, of course, entirely a matter of sur- mise. There is no apparent reason why there should be. Yet the infected Stegomyiz have almost certainly become so in a house, and with their very domestic habits must be found out of doors, where they would be subject to conveyance by the wind in much smaller numbers than the uninfected insects, and consequently a lesser number of them would be conveyed aérially. Observation is needed on this subject—the distance (across water) that Stegomyiz are aérially conveyed. Conveyance by railroads and vessels.—The yellow fever mosquito may be conveyed from one place to another in the railway car. I cap- tured one in a day coach en route between Donalsonville and Bain- bridge, Ga., in August, 1905. My experience in traveling by rail, both in Mexico and in the southern part of the United States, leads me to believe that the number thus conveyed is very small, so that the chance of conveying one that is infected is probably very slight. Distribution by vessels may not infrequently be observed. They have been found on steam vessels, but much more commonly and in greater numbers on sailing vessels, because the latter are more likely to present easily accessible breeding places. It can hardly be doubted that the outbreaks of yellow fever in such northern cities as Balti- more, Philadelphia, New York, Boston, and Quebec were due to the ii importation on sailing vessels of infected mosquitoes. These in pro- portion as they found conditions favorable, multiplied more or less rapidly and abundantly and produced epidemics which were more or less closely confined to, or in the neighborhood of, the shipping. Geographic distribution.—The Stegomyia calopus has been found to be one of the most widely distributed of mosquitoes. It is primarily a tropical insect, but has extended north and south along lines of travel, establishing itself permanently wherever the conditions of temperature and moisture are favorable. Speaking broadly, it belts the globe between 38° north and 38° south latitude. Within the United States the points at which it has been found, with few exceptions, ‘‘fall within the limits of what are known as the tropical and lower austral zones. These life zones include practically all of the southern United States which border on the Atlantic Ocean and the Gulf of Mexico, with the exception of those portions of Virginia, North and South Carolina, Georgia, and Alabama which constitute practically the foothills of the Appalachian chain; in other words, western Virginia and North Carolina, the extreme northwest- ern corner of South Carolina, the northern part of Georgia, and the extreme northeastern corner of Alabama. Further than this, the lower austral zone includes the western half of Tennessee, the western corner of Kentucky, the extreme southern tip of Illinois, the south- eastern corner of Missouri, and all of Arkansas except the northern portion. It also includes the southern portion of Indian Territory, southern Arizona, and some of northern Arizona, and southern strips in Utah, Nevada, and California. “In the greater part of the territory thus indicated, and where the climate'is not too dry, Stegomyia fasciata will, with little doubt, upon close search, be found. <