26 



PROTOZOA 



\ 



Fig. 20 



Fig. 21 



Fig. 20 — Spirocheta Italhi- 

 anii (Doflein), 



Fig. 21 — Spirocheta plicor 

 tilis (Doflein). 



Fig. 22 



Treponema 

 pallidum 

 (Doflein). 



Order 1. SPIROCHETIDA. 



Body elongate, spiral, with or without an undulating membrane; 

 flagellum very short or absent; nucleus diffuse: 1 family. 



Family SPIROdEETIDAE. 



With the characters of the order: 3 genera. 

 1. Spirocheta Ehrenberg. Undulating membrane but 

 no flagellum present: about a dozen species; 

 mostly parasitic. 



S. balbianii (Certes) (Fig. 20). Length ,02 

 to .18 mm.; broad membrane present; ends 

 rounded: in the digestive tract of the oyster, 

 often in the crystalline style. 



S. plicatilis Ehr. (Fig. 21). 

 Length .08 to .2 mm.; narrow 

 membrane present; ends rounded: 

 in stagnant water. 



2. Treponema Schaudinn. Fla- 

 gellum but no undulating mem- 

 brane present: about 8 species. 

 T. pallidum Schaudinn (Fig. 22). Body cylindrical, without 

 membrane, .015 mm. long ; ends tapering, ending each in a fine flagellum : 

 in syphilitic lesions. 



Order 2. MONADIDA. 



Body usually without shell and more or less amoeboid, with 1 or 2 

 large flagella at the forward end and often 1 or more secondary flagella ; 

 no mouth : 5 families. 



Key to the families of Monadida here described: 



Oi Pseudopodia present 1. Rhizomastigidae 



ttj Pseudopodia absent. 

 6, One flagellum present. 



Ci Body not in a cup 2. Cercomonadidae 



Cj Body in a cup 3. Codonecidae 



6, Two flagella present 4. Heteromonadidae 



Family 1. EHIZOMASTIGIDAE. 



Simple forms without mouth and with 1 or 2 flagella; occasionally 

 with either lobosc pseudopodia like a rhizopod or stiff radial ones like 

 a heliozoan ; food taken at any part of the body : G genera. 



Mastigam(Eba F. E. Schulze. Body irregular in form with several 

 pseudopodia which disappear when the animal swims, and one long 

 flagellum: 6 species; in fresh and salt water. 



