472 Malaria 



others develop into a chronic cachexia, with profound anemia and 

 complete incapacitation for physical or mental effort. The discovery 

 of Peruvian or Jesuits' bark, and its introduction into Europe by the 

 Countess del Cinchon, the wife of the Viceroy of Peru, about 1639, 

 marked an important epoch in the study of malarial fever. The 

 isolation of its alkaloids, quinin and cinchona, begun in 1810 by 

 Gomez and perfected in 1820 by Pelletier and Coven tou, a second 

 great epoch. But the most important epoch began in 1880, when 

 Charles Louis Alphonse Laveran,* a French physician engaged in the 

 study of malarial fever in Algeria, announced the discovery of a 

 parasite, to which he gave the name Plasmodium malariae, in the 

 blood of patients suffering from the disease. His observations were 

 immediately confirmed, Biitschli recognizing the parasitic nature 

 of the bodies observed. For the discovery he was awarded the Bre- 

 ant prize. 



Laveran, however, threw no light upon the source of infection, and 

 malaria continued to be described as a miasmatic disease. 



It was, however, recognized that there were different types of para- 

 sites corresponding to the different clinical forms of the disease, and 

 Golgif succeeded in correlating the various appearances of the para- 

 sites so as to express their life cycles. But in spite of the interesting 

 and important work of Golgi, Celli, Bignami and Marchiafava, and 

 many others, no progress was made in accounting for the entrance of 

 the parasites into the human body. 



This problem had long interested Sir Patrick Manson, who had 

 devised a theory which, though wrong in detail, proved in the end to 

 open the door to the next important discovery. Finding that the 

 malarial parasites could not be shown to leave the body in any of its 

 eliminations, and remembering that the same was true of the filarial 

 worms and their embryos, Manson came to the conclusion that they 

 must be taken out of the blood by some suctorial insect. The one 

 naturally first considered was the mosquito, which was known to 

 abound wherever malaria prevailed. Examining mosquitoes that 

 had been permitted to distend themselves with the blood containing 

 the parasites, Manson found that in the stomach of the insect the 

 peculiar phenomenon known as "flagellation," long before observed 

 by Laveran, took place in the parasites, giving rise to long, slender, 

 lashing, and, finally, free-swimming filaments. These, he conjec- 

 tured, might be the form in which the parasites left the mosquito 

 to infect the swamp water, with which human infection eventually 

 was brought about. Here Manson failed, but while he was investi- 

 gating he explained the whole matter to Major Ronald Ross, who 

 was soon to go to India, and whom he advised to make the matter a 

 subject for study when he arrived at his destination. RossJ ac- 

 cepted the opportunity that soon presented itself, and, after a most 



* " Accad. d. M6d.," Paris, Nov. 28 and Dec. 28, 1880. 

 t "R. Accad. di Medicina di Torino," 1885, xi, 20. 

 i "Indian Medical Gazette," xxxm, 14, 133, 401, 448. 



