II. FLAGELLATA: AUTOFLAGELLATA 



181 



spirally coiled threads (elaters). When wet, as by rain, the elaters or capillitium 

 expand, rupture the sporangium and scatter the spores. The spores germinate 

 in water or on moist surfaces, and from each comes out a small amceba-like 

 embryo, frequently furnished with a llagellum (fig. 132). Several of these 

 embryos fuse to form a plasmodium: -Ethalium septicum, flowers of tan, plas- 

 modium yellow, on spent tanbark; Arcyria (fig. 133), Plasmodiophora brassica;, 

 par aside in cabbage. 



Class II. Flagellata (Mastigophora). 



In many Rhizopoda (p. 172) the pseudopodia disappear at the time 

 of reproduction and are replaced by one or two flagella; others have, be- 

 sides pseudopodia, permanent flagella. Such flagellate spores and flagel- 

 late Rhizopods form the transition to the Mastigophora, which arc per- 

 manently flagellate, the flagella serving as organs of locomotion and 



feeding. 



The three orders must be described separately. 



Order I. Autoflagellata. 



The Autoflagellata form a polymorphic group. The 

 free forms are usually oval, with a nucleus in one end 



FIG. 134. FIG. 135. FIG. 136. FIG. 137. 



FIG. 134. Englena riridis (after Stein), c, contractile vacuole; ;/, nucleus; o, 

 pigment (eye) spot. 



FIG. 135. Dinobryon sertularia (after Stein), a, a parasitic flagellate often found 

 in the lorica; b, contractile vacuole; n, nucleus. 



FIG. 136. Conocladium umbelhitum (after Stein). 



FIG. 137. Chilimonas paranurcium (after Butschli). oe, cytostome; n, nucleus; v, 

 contractile vacuole. 



and a contractile vacuole in the other. At the anterior end there is 

 often a red or brown eye-spot (tig. 134) which gives these forms 

 great sensitiveness to light. In the parasitic forms the eye-spot and 



