UICROBIAI. DISEASES OF MAN AND ANIMALS. 



683 



blood is being sucked. The entry of a sporozoite within a red cell recommences the 

 cycle of development which has just been described If the adult sexual parasites are 

 not taken up by a mosquito they die, but some of the female forms may live for years 

 and then divide, without a precedent fertilization, to produce several young parasites. 

 It is possible for sporozoites to enter eggs lying in the ovaries of infected mosquitoes; 

 it is probable that mosquitoes, hatched from such eggs, inherit the infection from their 

 parent and that they, also, are able to transmit malaria. 



In fresh preparations of blood, a malarial parasite is seen as a body of varying size, 

 which is more refractile and of a lighter color, than the red cell which contains it. It 



o 



SCHIZOCONY (Asexual Generation) 

 in MAN. 







50 



'e e { 



Macroffamete($) -0 (&)Microcfamete 



Sporozoites. 



SPOROGONY (Sexual Generation) 

 in the MOSQUITO 



vermicuic. 

 Oocyst. 

 Oocyst wit A Sporob lasts. 



FIG. 126. Diagram illustrating the human and mosquito cycles of existence of 

 the malaria parasite. (After Martin's General Pathology from Jackson.} 



has distinct amoeboid movement and the pigment granules lying in it are in active 

 motion. In preparations, stained by a modification of Romanowsky's method every 

 malarial parasite is seen to possess a definite purple nucleus surrounded by blue-stain- 

 ing cytoplasm. Young parasites measure less than a fifth of the diameter of a red cell 

 in width; adult parasites may completely fill the cell which contains them. Malarial 

 pigment is the waste product which results from the digestion of the haemoglobin of the 

 red cells by a malarial parasite; consequently, since they have digested more hemo- 

 globin, the older parasites contain more pigment than do the younger ones. A mature 

 asexual parasite is segmented into a number of divisions, each of which becomes a 



