210 PROBLEMS RELATED TO SINGLE-CELLED ANIMALS 



bacteria in this regard, since so many more bacterial diseases have 

 now been discovered. Nevertheless, the fact that certain protozoa 



To cerebrospinal fluid causing sleeping 

 aickness and death. 



T>ansmisston by 

 bite of tsetse fly. 



^ Man .Antelope, etc 



& 



Xrypanosomea 



in human blood causing 

 Trypanosome jester- 



Transmission by bte 

 of tsetse fly^. 



Tsetse ?\y 



Forms in salivary glands 

 dy for re- infection. 

 \ZO"'-50"' day) 



Crlthidial /orms in 



salivacy glands 

 {3. or a days latert 



Forms In midauf-,(Va/ 

 after infective meal;. 



newly arrived form in 

 .salivary aland. 

 U2^toJo"'dcty3.) 



Long slender torms In proventriculus. 

 f about I0*4ol5*''day5) 



Fig. 109. — Life history of Trypanosoma gambiense. X 1500. 



(From Chandler, "Animal Parasites and Human Disease," John Wiley and Sons, copy- 

 right, 1922, reprinted by permission.) 



are important as causes of infectious diseases, along with the rela- 

 tion of insects to disease, is among the great discoveries of medi- 

 cine in recent years. 



