INSECTS IN RELATION TO OTHER ANIMALS 301 
ee 
The malaria ‘‘ germ,” discovered in 1880 by the French 
army surgeon Laveran, may be found as a pale, amoeboid 
organism (Plasmodium, Fig. 269) in the red blood corpus- 
cles of persons afflicted with the disease. This organism 
(schizont, 2) grows at the expense of the haemoglobin of the 
corpuscle ( ?—5) and its growth is accompanied by an increasing 
deposit of black granules (imelanin), which are doubtless 
excretory in their nature. At length, the amcebula divides 
into many spores (merozoites, 0), which by the disintegration 
of the corpuscle are set free in the plasma of the blood. Here 
many if not most of the spores, and the pigment granules as 
well, are attacked and absorbed by leucocytes, or white blood 
corpuscles, while some of the spores may invade healthy red 
corpuscles and develop as before. The period of sporulation, 
9 
as Golgi found, is coincident with that of the * chill” experi- 
enced by the patient; and quinine is most effective when ad- 
ministered just before the sporulation period. ‘The destruc- 
tion of red blood corpuscles explains the pallid, or anemic, 
condition which is characteristic of malarial patients. In 
three or four days the number of red corpuscles may be re- 
duced from 5,000,000 per cubic millimeter—the normal num- 
ber—to 3,000,000; and in three or four weeks of intermittent 
fever, even to 1,000,000. 
Three types of malaria are recognized: (1) the tertian, in 
which the paroxysm recurs every two days; (2) the quartan, 
in which it happens every third day; and (3) the estivo- 
autumnal type (Fig. 269). These three kinds are by some 
forming microgametes. 9b, resting cell, bearing six flagellate microgametes (male). 
to, fertilization of a macrogamete by a motile microgamete. The macrogamete next 
becomes an oodkinete.’ rz, odkinete, or wandering cell, which penetrates into the wall 
of the stomach of the mosquito. 172, odkinete in the outer region of the wall of the 
stomach, i. e., next to the body cavity. 73, young oocyst, derived from the odkinete. 
I4, oocyst, containing sporoblasts, which are to develop into sporozoites. 15, older 
odcyst. 16, mature odcyst, containing sporozoites, which are liberated into the body 
cavity of the mosquito and carried along in the blood of the insect. 17, transverse 
section of salivary gland of an Anopheles mosquito, showing sporozoites of the malaria 
parasite in the gland cells surrounding the central canal. 
1-6 illustrate schizogony (asexual production of spores); 7-16, sporogony (sexual 
production of spores). 
After Grasst and LEucKART, by permission of Dr. Carl Chun. 
