NUTRITION 39 



(c. vac\ anterior flagellum (fl. i), and coiled ventral flagellum (Jl. 2) 

 by which the organism is anchored ; A 2 shows the position at the 

 forward limit of the spring, the ventral flagellum being fully extended. 



B' B 3 , three stages in the longitudinal fission of the anchored form. 



c' c 3 . Three stages in the transverse fission of the same : Jl. i 1 , 

 rudiment of newly formed anterior flagellum. 



D 1 D 3 , three stages in the fission of the free-swimming form : Jl. 2 1 , 

 rudiment of the newly-formed ventral flagella. 



E', free-swimming and anchored forms about to conjugate : E-, com- 

 mencement of conjugation : E 3 , E 4 , two stages in the development of 

 the zygote : E 5 , the fully formed zygote : E 6 , dehiscence of the zygote 

 and emission of spores. 



F 1 F 4 , four stages in the development of the spores. After 

 Dallinger. 



fact that it possesses neither mouth nor pseudopods, examples 

 have been kept under observation for hours together by 

 trained microscopists, and have never been observed to 

 ingest the bacteria or other particles dead or alive contained 

 in the fluid. There remains only one way in which 

 nutrition can take place, namely, by absorption of the 

 proteids and other nutrient substances in the solution, i.e., 

 by these substances diffusing into the water of organization 

 of the monad. Whether the proteids are rendered diffusible 

 by the process of decomposition alone, i.e., by the action 

 of bacteria (see p. 90), or whether a kind of surface 

 digestion takes place, the protoplasm of Heteromita con- 

 verting the proteids in immediate contact with it into pep- 

 tones or allied compounds, is not certain. 



Thus Heteromita feeds neither by taking solid pro- 

 teinaceous food into its interior (holozoic nutrition) nor by 

 decomposing carbon dioxide and combining the carbon with 

 water and mineral salts (holophytic nutrition), but by absorb- 

 ing decomposing proteids and other nutrient substances in 

 the liquid form ; this is the saprophytic mode of nutrition. 

 It will be seen that the main difference between saprophytic 

 and holozoic nutrition is that in the former digestion, i.e., 

 the process of rendering food-stuffs soluble and diffusible, 



