MALARIAL PARASITOLOGY 



511 



The male mosquito is readily told from the female by its plumed 

 antennae, those of the female being inconspicuous. 



The Cycle in the Mosquito. If an ordinary mosquito (culex) is allowed 

 to imbibe the blood of a malarial patient whose blood shows gameto- 

 cytes there will be simply a digestion of such blood in the mosquito, 

 but no anatomical changes. If, however, an anopheles mosquito 

 ingests such blood, immediate changes follow. It should be remembered 

 that only female mosquitoes bite; hence, they alone can be responsible 

 for the spreading of the disease. 



The flagellation of the male parasite described above will promptly 

 take place; the free flagella conjugate with the female element in a 

 manner comparable to the impregnation of the ovum of higher animals 

 by spermatozoids. 



FIG. 156 



Schema of double cycle. 

 L. B. Goldhorn, fee. 

 2904. 



rest-body in 



wall of stomach. 



\O6kinet which penetrates 

 \$)lining of ttomach-wall 



Mosquito 



of mosquito. 



circle-asexual reproduction : 

 chninber observation shows no flagellation. 

 Outer circle-formation of (sexual) gametes; 

 moist-chamber observation shows flagellation. 



Infection of man through gastro-intestinal and 

 respiratory tract, the infected mosquito dying 

 in water, drying in air or sucking plant-juices, 

 infecting fresh vegetables (theoretical) 



This product of conjugation remains for a number of hours in the 

 juices of the chyme stomach of the mosquito, changing gradually from 

 a spherical, immotile body into an elongated wormlet endowed with 

 motility. This penetrates the epithelial lining of the stomach and 

 rests in the tissues; here it changes into an oval, then into a round body, 

 which grows in the course of the next few days enormously, forming a 

 cyst which projects into the body cavity. Meanwhile the chromatin 

 will have been very active. It will have divided into numerous nuclei, 

 which become arranged around inactive portions, and filamentous 

 sporozoites develop from this chromatin. These sporozoites ultimately 

 fill the cysts, which rupture, setting them free into the cavity of the 

 mosquito's body; they then make their way to a glandular structure in 

 the thoracic cavity of the insect, the so-called salivary gland, which in 

 turn is in immediate connection with the biting and sucking apparatus. 

 If now such an infected mosquito "bites" a human being the lubri- 



