GENERAL PHYSTOLOGY' 199 



be separated by oxidation from the alcohol groups and the latter 

 broken up into free oxygen and formaldehyde or directly into sugar. 

 Some such process apparently occurred in the experiment cited, 

 but no synthesis of sugar or regeneration of the chlorophyll molecule 

 took place. On the contrar\', the chromogen material was soon 

 broken down through displacement of the magnesium by hydrogen, 

 due to the action of the increasing quantity of formic acid and the 

 reaction stopped. In the living plant it is conceivable that through 

 energy from sunlight, formaldehyde, if formed, is condensed to 

 sugar, while the nitrogen-holding compound, chromogen, forms 

 again the complex chlorophyll molecule by regeneration through 

 union with CO2 and H2O with the aid of energ\' from sunlight. On 

 this hypothesis, starch or sugar formation is a result of protein 

 metabolism acting with the energy of sunlight, while (O2 and H2O 

 are foods or raw materials necessary for upbuilding in chlorophyll 

 regeneration. Protein metabolism in plants and animals would 

 thus be placed on a similar basis, katalytic action breaking down 

 the complex protein molecule, gi^'ing rise to a metai)lastid starch 

 and a chromogen radical capable of taking on raw materials (food) 

 necessary for its regeneration. On such an hypothesis the essential 

 use of CO2 and H2O would be as food for the plant in building up 

 its particular type of protein— r/2., chlorophyll, and until that 

 chlorophyll is formed no starch or sugar is produced. 



(rf) Heterotrophic Xtitriti(j)i.— The ability of certain organisms to 

 live on manufactured foods in the light and to live equally well on 

 proteins manufactured by other living organisms, has been known 

 for many years. Biitschli called attention to it in the case of 

 ChromuUna (1884) and in some Dinoflagellates; Ternetz (1912) 

 and Zumstein (1900) demonstrated experimentally that Euglena 

 gracilis can live almost equally well in the light or in the absence of 

 light, and more recently Pascher has shown that practically all of 

 the Chrysomonadida possess this power, while the assertion is 

 made and practically substantiated by experiment, that "all colored 

 flagellates incline to saprophytism and combine in Nature almost 

 regularly both types (holophytic and saprophytic) of nutrition" 

 (1914, pt. I, p. 11). Indeed, the experiments of Zumstein and of 

 Ternetz show that with exclusively organic nourishment EucjJena 

 races appear in which the chromatophore apparatus is temporarily 

 gone, and Ternetz, at least, succeeded in cultivating races of Euglena 

 gracilis in which the chromatophores were said to be permanently 

 lost. 



It is quite probable that saprophytic flagellates have been derived 

 through forms with the double or combined modes of nutrition 

 from the strictly autotrophic types. Pascher states, in this con- 

 nection: "Flagellated forms are present which possess distinct 

 but reduced cliromatophores incapable of extensive functions; 



