GENERAL PHYSIOLOGY 199 



Even cellulose is said by Stole to be digested by this organism and 

 Schaudinn made the same observation on the Foraminiferon Cal- 

 cituba polymorpha. In Foraminifera generally, according to Jensen, 

 and in myxomycetes, according to Wortmann, Lister and Cela- 

 kowsky, starch may be similarly digested. The flagellates appar- 

 ently have in some cases, at least, the same power of dissolving 

 starch. Thus, Protomonas amyli and Phyllomitus augustatus eat 

 practically nothing but starch, a fact indicating the action of 

 appropriate digestive ferments. The Hypermastigidae which are 

 abundant in white ants (termites) are unusual in their ability to 

 digest cellulose. It has been shown that these flagellates live as 

 symbionts with their termite hosts digesting the wood eaten by 

 them. The termites die if deprived of their protozoan symbionts 

 by heating or by oxygenation; the protozoa die if the wood diet of 

 the termites is stopped (Cleveland, 1923). 



In few Protozoa has the actual digestion of fat been observed. 

 Under experimental conditions, ingested fats are usually carried 

 along unchanged in the protoplasm. We cannot state arbitrarily, 

 however, that fats are not emulsified and used as food. On the 

 contrary, it is difficult to account for the presence of oils and fat 

 bodies in varying quantities in all groups of Protozoa under any 

 other assumption, despite the negative results of Stamiewicz (1910) 

 and of Nirenstein (1909). Positive results indeed have been ob- 

 tained by Dawson and Belkin (1928), who injected oils of different 

 kinds into Amoeba proteus; of these 8.3 per cent of cod-liver oil was 

 digested, 8.2 per cent of olive oil, 4 per cent of cotton-seed oil, 

 3.5 per cent of sperm oil and 1.4 per cent of peanut oil. 



Saprozoic Nutrition. — In holozoic nutrition the food substances 

 are in the form of complex proteins, carbohydrates and fats, making 

 up the bodies of the various organisms ingested. In saprozoic 

 and saprophytic nutrition the food substances are less complex 

 chemically, consisting of materials dissolved out of the disintegra- 

 ting bodies of animals and plants. These are taken in, not through 

 the agency of specialized oral motile organs, nor through a definite 

 mouth, but are absorbed through the body wall. Many of the 

 smaller types of flagellates obtain their nutriment in this way, 

 extracts or infusions of animal or plant tissues containing various 

 salts and organic compounds forming excellent culture media for 

 such Protozoa. Little is known, however, of the chemical make- 

 up of such fluid substances, nor is it known whether they are 

 prepared for absorption by chemical processes due to the activity 

 of the receptive organism; nor is there any evidence to indicate 

 processes of digestion subsequent to their absorption. The general 

 assumption, based upon the thriving cultures in infusions of dis- 

 integrating animal and plant matter, has been that dissolved 



