PROTOi^OA on SIMlMJvST ANIMALS. 14e 



tlu! ciiiise of Malaria or A^ne. For (Mjuntless iroiierations man has 

 sulfered from this mysterious malady, and inimmeraljlc theories, sucli 

 as its bein.if due to the effects of the bad air— hence the name 

 " ^Falaria "— of marshes and soils, rai)id variations of tem[KTature, 

 heat of the sun, &c., &c., have been broui^ht forward to account for it. 



It is only within the last, quarter of a century that the reiil cauiic 

 has become delinitely known. In \Hs2 fiiiveran, a French docU^)r 

 at Algiers, found the blood of patients suffering frum malaria in- 

 fested with an organism to which he gave the name Oscillnrin 

 malarm, under the impression that it was a vegetable ; and, further, 

 he showed that the symptoms of the patient resulted from the 

 ])rcsence of this organism in the blood. Later, the parasite was 

 found to be a Sporozoon, and was named Lnverania malar i^n. Tlu,- 

 next great discovery was that of the means whereby human beings 

 became infected. The labours of Ross, Grrassi, and others showed 

 that the agency whereby the malarial parasite was inoculated intotlie 

 blood was that of the stab of the blood-sucking mosquito. Anopheles. 

 It was found that the mosquito was not a mere carrier, Init a true 

 intermediate host, in whose body the malarial germs underwent the 

 sexual phase in their life history. A Jjrief account of the life cycle 

 of one of these blood parasites will now be given. 



Pernicious malaria is caused by the Ilajmosporidian Lnverania 

 malarm. An Anopheles infected with the germs (exotospores) of 

 Laverania stabs the skin of a human being with its piercing and 

 stictorial proboscis. The mosquito [)ours into the wound a tiny drop 

 of its saliva, which is crowded with the Laveraaia germs. 



Each minute spindle-shaped exotospore (Fig. IOf, a) attacks and 

 penetrates a red blood cell, and becomes an amrebula, which grows at 

 the expense of the blood cell (Fig. IOf, l),c) ; when mature the amcebula 

 divides up into a rosette-like group of " enhiemospores " (Fig. lOF, d). 



The blood cell breaks down and the liberated enluemospores 

 (Fig. 1()F, e) proceed to attack other blood cells within which they 

 grow into amcebula), which again divide up into rosettes. In tertian 

 ague, due to Plasmodium viva.r, this cycle takes forty-eight iioui-s, 

 and the onset of the fever every third day coincides with the 

 liberation of enhicmospores and the attacking of fresh blood cells ; 

 in quartan ague, due to Plttsmadimnmaliiriic, the cycle takes .seventy- 

 two hours. 



only has Man's life and health been seriously affeited, but intereommuuioa- 

 tioii prevented by the extermination of domostic uniiniils. AlreiKly. tliiiiik> 

 to the labours of men of science, localilies formerly postiforous liiivc boromo 

 salubrious. 



