MALARIA. 361 



of hydrogen and carbon — methane or 'marsh-gas.' In short, we now 

 know that the air in the vicinity of marshes is not deleterious because of 

 any special kind of bad air present in such localities, but because it con- 

 tains mosquitoes infected with a parasite known to be the specific cause 

 of the so-called malarial fevers. This parasite was discovered in the 

 blood of patients suffering from intermittent fevers by Laveran, a sur- 

 geon in the French army, whose investigations were conducted in Al- 

 giers. This famous discovery was made toward the end of the year 

 1880, but it was several years later before the profession generally began 

 to attach much importance to the alleged discovery. It was first con- 

 firmed by Eichard in 1882; then by the Italian investigators, Marchia- 

 fava, Celli, Golgi and Bignami; by Councilman, Osier and Thayer in 

 this country, and by many other competent observers in various parts 

 of the world. The Italian investigators named not only confirmed the 

 presence of the parasite discovered by Laveran in the blood of those 

 suffering from malarial fevers, but they demonstrated its etiological role 

 by inoculation experiments and added greatly to our knowledge of its 

 life history (1883-1898). The fact that the life history of the parasite 

 includes a period of existence in the body of the mosquito, as an inter- 

 mediate host, has recently been demonstrated by the English army sur- 

 geons Manson and Eoss, and confirmed by numerous observers, includ- 

 ing the famous German bacteriologist, Koch. 



The discoveries referred to, as is usual, have had to withstand the 

 criticism of conservative physicians, who, having adopted the prevailing 

 theories with reference to the etiology of periodic fevers, were naturally 

 skeptical as to the reliability of the observations made by Laveran and 

 those who claimed to have confirmed his discovery. The first conten- 

 tion was that the bodies described as present in the blood were not para- 

 sites, but deformed blood corpuscles. This objection was soon set at 

 rest by the demonstration, repeatedly made, that the intra-corpuscular 

 forms underwent distinct amoeboid movements. No one witnessing 

 these movements could doubt that he was observing a living micro- 

 organism. The same was true of the extra-corpuscular flagellate bodies, 

 which may be seen to undergo very active movements, as a result of 

 which the red blood corpuscles are violently displaced and the flagellate 

 body itself dashes about in the field of view. 



The first confirmation in this country of Laveran's discovery of 

 amoeboid parasites in the blood of malarial-fever patients was made by 

 myself in the pathological laboratory of the Johns Hopkins University 

 in March, 1886. In May, 1885, 1 had visited Eome as a delegate to the 

 International Sanitary Conference, convened in that city under the aus- 

 pices of the Italian Government, and while there I visited the Santo 

 Spirito Hospital for the purpose of witnessing a demonstration, by Drs. 

 Marchiafava and Celli, of that city, of the presence of the plasmodium 



