PROTOZOA 



25 



Vertebrates and Arthropods. Euglena viridis often exists in 

 such numbers as to turn the water green, and a species of 

 Haematococcus is responsible for the red snow of the Arctic 

 regions. Many of them, such as Polytoma, thrive in putrid 



Fig. 19. — Proterospongia Haeokeli, Sav. Kent, x 800. 



1. Nucleus. 



2. Contractile vacuole. 



3. Collar. 



4. Flagellum. 



5. Amoetoid individual sunk in sup- 



porting jelly. 



6. Other individuals undergoing 



fission. 



7. Individual with collar contracted. 



8. Individual divided up into numter 



of spores (miorogonidia). 



9. Jelly-lilce supporting matrix. 



liquids, such as the water of macerating tubs, and these forms 

 are mostly saprophytic. 



Some of the lower forms are apt to withdraw their flagellum 

 and become amoeboid {Oilwphrys) ; in others {Gercomonas), the 

 posterior end of the body is very apt to throw out pseudopodia, 

 and the young of many species exhibit amoeboid movements. 

 These facts support the view that the Flagellata are derived 

 from the Gymnomyxa; and indeed there are certain forms 

 which might equally well find a place in the class Proteo- 

 myxa. 



Class II. RhynchoflageUata. 



This class contains but one or two genera. One of them, 

 Nodiluca, attains a large size : ^ of an inch in diameter. It is 



