92 



PROTOZOOLOGY 



cle-bearing forms, the defecation takes place either through the 

 cytopyge located in the posterior region of the body or through 

 an aperture to the vestibule (in Carchesium). Permanent cyto- 

 pyge is lacking in some forms. In Fabrea salina, Kirby (1934) no- 

 ticed that a large opening is formed at the posterior end, the con- 

 tents of food vacuoles discharged, and the opening closes over. 

 At first the margin of the body is left uneven, but soon the evenly 

 rounded outline is restored. The same seems to be the case with 

 Spirostomum (Fig. 36), Blepharisma, etc. 



Fig. 36. Outline sketches showing the defecation process in 

 Spirostoni^un ambiguum (Blattner). 



Holophytic (autotrophic, phytotrophic) nutrition. This is the 

 type of nutrition in which the Protozoa are able to decompose 

 carbon dioxide by means of chlorophyll contained in chromato- 

 phores (p. 78) in the presence of the sunUght, liberating the oxy- 

 gen and combining the carbon with other elements derived from 

 water and inorganic salts. The pyrenoids (p. 79) are inseparably 

 connected with the reserve carbohydrate formation in this nutri- 

 tion. Aside from the Phytomastigina, chromatophores were defi- 

 nitely observed in Cyclotnchium meunieri (Fig. 230, o) by Powers. 

 In a number of other cases, the organism itself is without chro- 

 matophores but is apparently not holozoic, because of the presence 

 of chlorophyll-bearing organisms within it. For example, in the 

 testacean Paulinella (Fig. 155, c) in which occur no food vacuoles, 

 chromatophores of peculiar shape are always present. The latter 

 appear to be a species of algae which holds a symbiotic relation- 

 ship with the testacean, and perhaps it acts for the sarcodinan as 

 the chromatophores of the Phytomastigina. 



Saprozoic (saprophytic) nutrition. In this nutrition, the Proto- 

 zoa obtain nourishment by diffusion through the body surface. 

 This is accomplished without any special organellae. Perhaps the 



