SUBDIVISION INTO GENERA 



319 



parasites, but they attain a higher degree of development. In their cycle 

 are found all four types — leishmania, leptomonas, crithidia, and trypano- 

 sonie. Here, again, infection is passed on by encysted forms. 



4. Flagellates of the genus Leishmania resemble those of the genus 

 Leptomonas in having only the leishmania and leptomonas forms, but they 

 differ in having both a vertebrate and an invertebrate host. Both the 

 leishmania and leptomonas forms may occur in either host. It is presumed 



GENERIC TITLES 



33 



m 

 O 



m 

 -o 



-I 



O 



z 

 s> 



C/) 



FLAGELLATE TYPES 



c^rz!:^ 



:^ 



TRYPANOSOME 



TRYPANOSOME 



GRITHIDIA 



LEPTOMONAS 



LEISHMANIA 



(2 

 LEISHMANIA 



Fig. 153. — Diagram of Classification of the Trypanosomes and Allied 

 Flagellates. (After Wenton, 1913, 1921.) 



that infection passes from invertebrate to vertebrate or from vertebrate 

 to invertebrate, but the exact mechanism of this is not yet known. 



5. Flagellates of the genus Phytomonas, which resemble those of the 

 genus Leptomonas, but differ in having both an invertebrate and plant 

 host. 



6. Flagellates of the genus Trypanosoma have also a vertebrate and 

 invertebrate host. They resemble those of the genus Herpetomonas in 



