PROTOZOA on simplest animals. 
14m 
the cause of Malaria or Ague. For countless generations man has 
suffered from this mysterious malady, and innumerable theories, such 
as its being due to the effects of the bad air — hence the name 
“ Malaria of marshes and soils, rapid variations of temperature, 
heat of the sun, &c., &c., have been brought forward to account for it. 
It is only within the last quarter of a century that the real cause 
has become definitely known. In 1882 Laveran, a French doctor 
at Algiers, found the blood of patients suffering from malaria in- 
fested with an organism to which he gave the name Oscillaria 
malaria, under the impression that it was a vegetable ; and, further, 
he showed that the symptoms of the patient resulted from the 
presence of this organism in the blood. Later, the parasite was 
found to be a Sporozoon, and was named Laverania malaria. The 
next great discovery was that of the means whereby human beings 
became infected. The labours of Ross, Grassi, and others showed 
that the agency whereby the malarial parasite was inoculated into the 
blood was that of the stab of the blood-sucking mosquito, Anopheles. 
It was found that the mosquito was not a mere carrier, but a true 
intermediate host, in whose body the malarial germs underwent the 
sexual phase in their life history. A brief account of the life cycle 
of one of these blood parasites will now be given. 
Pernicious malaria is caused by the Hgemosporidian Laverania 
malaria. An Anopheles infected with the germs (exotospores) of 
Laverania stabs the skin of a human being with its piercing and 
suctorial proboscis. The mosquito pours into the wound a tiny drop 
of its saliva, which is crowded with the Laverania germs. 
Each minute spindle-shaped exotospore (Fig. 10f, a ) attacks and 
penetrates a red blood cell, and becomes an amoebula, which grows at 
the expense of the blood cell (Fig. 10f, l,c) ; when mature the amoebula 
divides up into a rosette-like group of “ enhsemospores ” (Fig. 10f, d). 
The blood cell breaks down and the liberated entnjemospores 
(Fig. 10f, e) proceed to attack other blood cells within which they 
grow into amoebulae, which again divide up into rosettes. In tertian 
ague, due to Plasmodium vivax, this cycle takes forty-eight hours, 
and the onset of the fever every third day coincides with the 
liberation of enhasmospores and the attacking of fresh blood cells ; 
in quartan ague, due to Plasmodium malaria, the cycle takes seventy- 
two hours. 
only has Man’s life and health been seriously affected, but intercommunica- 
tion prevented by the extermination of domestic animals. Already, thanks 
to the labours of men of science, localities formerly pestiferous have become 
salubrious. 
