no 



Insects and Disease 



takes them to sporulate. Let us begin with the 

 parasite after it has been introduced into the blood 

 and trace its development there. At first it is slen- 

 der and rod-like in shape. It has some power of 

 movement in the blood-plasm. Very soon it at- 

 tacks one of the red blood-corpuscles and gradually 

 pierces its way through the wall and into the cor- 

 puscle substance (Fig. 99); here it becomes more 

 amoeboid and continues to move about, feeding all 

 the time on the corpuscle substance, gradually de- 

 stroying the whole cell. As the parasite feeds and 

 grows there is deposited within its body a blackish 

 or brownish pigment known as melanin. 



During the time that the parasite is feeding and 

 growing it is also giving off waste products, as all 

 living forms do in the process of metabolism, but as 

 the parasite is completely inclosed in the corpuscle 

 wall these waste products cannot escape until the 

 wall bursts open. After about forty hours if the 

 parasite is vivax or about sixty-five hours if it is 

 malaricB it becomes immobile, the nucleus divides 

 again and again and the protoplasm collects around 

 these nuclei, forming a number of small cells or 

 spores, as they are called. In about forty-eight or 

 seventy-two hours, depending on whether the para- 

 site is vivax or malaria the wall of the corpuscle 

 bursts and all these spores with the black pigment 



