PKOTOZOA 



29 



is elongated and consists of a granular endoplasm and a thin 

 ectoplasm. The ectoplasm is produced to form a fine 

 undulating membrane ending in a flagellum. The ectoplasm 

 of the flagellum is differentiated to form a band which runs 

 along the edge of the undulating membrane to end in a body 

 called the blepharoblast. Near this is a nucleus-like body 

 called the kinetonucleus or parabasal body. A nucleus is 

 also present, and to distinguish it from the kinetonucleus it 

 has been called the trophonucleus. The parasite progresses 

 by the action of the flagellum, which is posterior. Schizogony 

 takes place in the blood of the vertebrate host, and some kind 



Trophonucleus 



Flagellum 



Kinetonucleus 



Undulating membrane 

 FIG. 12. Trypanosome. 



of sex development is supposed to occur in the invertebrate 

 blood-sucker. In the case of the Trypanosome, which causes 

 sleeping sickness, the insect host is the tse-tse fly. With 

 relation to sleeping sickness, two species of tse-tse flies and 

 two species of Trypanosomes have been described Glossina 

 palpalis and Trypanosoma gambiense and G. morsitans and 

 T. rJiodesiense. The genus Trypanosoma and its allies are 

 widely distributed in vertebrates, including fishes, marine 

 and fresh-water, and the invertebrate hosts are also varied. 

 Trypanosomes, moreover, appear in some cases to be confined 

 to invertebrate hosts. 



In consequence of the importance of the diseases in- 

 volved, Protozoology, like Bacteriology, has come to occupy 

 a prominent place in Medicine. 



