A CHAPTER ON INSECTS 129 



of the protoplasm of the corpuscle. It rapidly grows 

 and divides into a progeny of thirteen to eighteen 

 small spore-like individuals which are set free into the 

 blood by the bursting of the wall of the blood cor- 

 puscle. This sporulation occurs periodically and 

 corresponds to the attacks of chills followed by fever, 

 which attacks are intermittent, depending on the 

 life cycle of the parasite. 



There are two varieties liberated into the blood 

 stream, those in largest number being able to mul- 

 tiply by direct division, while the other kind consist 

 of germinal elements that require a different host and 

 a different set of conditions in order to unite and 

 complete their life history. Their union is a process 

 of fertilization and is accomplished in the blood of a 

 mosquito, in which animal they undergo a compli- 

 cated development, resulting finally, in an immense 

 number of spore-like individuals. 



The history of the first kind is more simple. They 

 bore their way into new corpuscles and repeat the 

 changes mentioned above. The number of corpus- 

 cles infested is continually multiplying so that soon 

 the blood becomes the seat of a prodigious number of 

 the malarial parasites. 



The rate at which they are produced varies with 



