38i 



Development in the blood. 



1. A large development of the indifferent trypanosome 

 takes place, causing an acute infection, 



2. The sexual forms appear. These parasites infect 

 leucocytes or rather young Hgb-free erythroblasts, so that 

 development goes on mainly in the internal organs. The sexual 

 forms are distinguished from the indifferent forms by their much 

 greater size They are much larger than the cells they attack, 

 and, in fact, take up the cell into their protoplasm They are 

 found in the blood as in T. noctuae, both in the resting stage 

 and in the motile trypanosome stage When the blood enters 

 the mosquito's stomach flagellation takes place, the makro- 

 gamete is fertilized, and the ookinet results, 



Trypanosomes and spirochaetes have been 

 found together with piroplasraata in cases of red 

 water in cattle, and it is suggested that possibly 

 piroplasniata develop in ticks by means of a 

 trypanosome stage. 



6. Tick Fever. — Ross and Milne have found 

 spirilla (scanty) in all cases examined by them 

 [vide p. 349). 



