356 



C. Development of the indifferent trypanosomes in the blood: 



1. Some of the larger forms sub-divide in the blood. 



2. The smaller forms apply themselves closely to the sur- 

 face of the red cells and gradually penetrate, they lose their 

 flagellum and new resemble young halteridia. 



3. Pigment appears in twenty-four hours. 



4. The parasites, however, again leave the red cell, chiefly 

 at night time, and again become trypanosomes though now 

 increased in size.- These changes also occur especially in the 

 internal organs, bone marrow, spleen, kidney, and liver. This 

 process is repeated several times till after six days the fully- 

 developed trypanosome and halterida stages are reached. 



5. The fully-developed trypanosome divides rapidly till 

 a largenumber of young flagellates are forrned, which go through 

 the same process until a massive infection of the red cells is 

 produced. The developmental cycle in the blood thus takes six 

 days. Whether in other species a formation of spores as in 

 malaria, and as originally described by Danilewsky, takes 

 place remains to be seen. 



A. The development of the ookinet ( ^ ) into the female trypanosome. 



I. By a similar process the female trypanosome results. 

 It is larger and stains more deeply than the indifferent form. 

 The membrane is less well-developed, the blepharoplast is 

 smaller, and the flagellum is shorter. It moves more slowly 

 and soon takes on the gregarine form in the stomach. 



B. The development in the mosquito. 



1. They are the most resistent forms and can be found in 

 the stomach two to three weeks after feeding, when all the 

 other forms have died. 



2. In this fasting condition they have penetrated the 

 epithelium, and resemble malarial zygotes. It is these forms 

 also by which the infection is transmitted to the egg as they 

 remain alive in the ovary, and these forms can also, by partheno- 

 genesis, give rise to all three forms, either in the stomach or in 

 its halteridium forrti in the blood. 



C. Development of 9 trypanosome in the blood. 



1. They enter the blood cells and grow slowly. 



2. They leave the red cell not as a trypanosome but in a 

 worm-like gregarine form. 



3. They eventually form the characteristic makrogamete. 

 At the end of the acute infection they are the only forms 



