APPENDIX C. 



MALARIAL FEVERS. 



It has now been conclusively proved that the malarial fevers 

 are protozoal infections, there being several species of parasite. 

 These belong to the hsemosporidia (a sub-class of the sporozoa), 

 which are blood parasites, infecting the red corpuscles of mam- 

 mals, reptiles, and birds. The parasite was formerly known as 

 the hcematozoon or Plasmodium malarim ; the term honmamaeba 

 is, however, now generally employed. It was first observed by 

 Laveran in 1880, and his discovery received confirmation from 

 the independent researches of Marchiafava and Celli, and later 

 from the researches of many others in various parts of the 

 world. Golgi supplied valuable additional information, especi- 

 ally in relation to the sporulation of the organism and the 

 varieties in different types of malarial fever. In this country 

 valuable work on the subject was done by Manson, and to him 

 specially belongs the credit of regarding the exflagellation of 

 the organism as a preparation for an extra-corporeal phase of 

 existence. By induction he arrived at the belief that the cycle 

 of existence outside the human body probably took place in the 

 mosquito. It was specially in order to discover, if possible, the 

 parasite in this insect, that Ross commenced his long series of 

 observations, which were ultimately crowned with success. After 

 patient and persistent search, he found rounded pigmented bodies 

 in the wall of the stomach of a dapple-winged mosquito (a 

 species of Anopheles) which had been fed on the blood of a 

 malarial patient. The pigment in these bodies was exactly 

 similar to that in the malarial parasite, and he excluded the 

 possibility of their representing anything else than a stage in 

 the life-cycle of the organism. He confirmed this discovery and 

 obtained corresponding results in the case of the proteosoma 

 infection of birds, where the parasite is closely related to that 

 of malaria. In birds affected with this organism, he was able 

 to trace all stages of its development, from the time it entered 



