//. FLAGELLATA: AUIOFLAGELLATA. 



201 



sit in small groups. There are great differences in the feeding 

 and in the organs connected therewith. Many feed like animals, 

 being provided with pseudopodia like the Rhizopoda or with a 

 mouth like the Infusoria. In the Choanoflagellata there is an 

 interesting structure, the collar. This is a funnel-like process of 

 the body protoplasm on which foreign particles are thrown by 

 the flagellum in the centre (fig. 136) and thence are conveyed 

 to the interior. (According to recent researches the collar 

 consists of a plasma membrane rolled up spirally with two turns. ) 

 Besides these animal forms are plant-like species which contain 

 chlorophy] (Volvocinae, Euglenidae) or brown chromatophores- 

 (Chromomonadineae), aiding in assimilation and enabling the 

 organism to produce paramylum or even starch. It is note- 

 worthy that forms which are plant-like in this respect are 

 closely allied anatomically to forms which resemble the animals. 

 Indeed, there are species which possess a cytostome without taking 

 solid nourishment, assimilating by means of chlorophyl or living 

 on fluid food (fig. 137). All this renders more difficult the syste- 



FIG. 137. 



FIG. 138. 



FIG. 137. Chilimonas paramcecium. (After Butschli.) oe, cytostome; n, nucleus; v, 



contractile vacuole. 

 FIG. 138. Flagellata. -4, Mastigamceba; B, Codosiga; (7, Bicoseca; D, Hexamita; E r 



Noctiluca, side view. 



matic valuation of the differences appearing in the food, and also 

 shows that the Flagellata have relations in different directions: 

 with the Rhizopoda, the Infusoria, and the lower plants. 



