GENERAL PHYSIOLOGY 193 



least, the same power of dissolving starch. Thus, Protomonas 

 ami/Ii and PhyUomitus augnstatus eat practically nothing but starch, 

 a fact indicating the action of appropriate digestion ferments. 

 The Hypermastigida^ 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 by the aid of glycogen. The 

 termites die if deprived by heating of their protozoan symbionts; 

 the protozoa die if the wood diet of the termites is stopped (Cleve- 

 land, 1923). 



In no protozoon has the actual digestion of fat been observed. 

 Under experimental conditions, ingested fats are carried along 

 unchanged in the protoplasm. We cannot state arbitrarily, how- 

 ever, that fats are not emulsified and used as food. On the con- 

 trary, 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). 



3. Z)f/ecfl//o?L— Undigested and indigestible remains are disposed 

 of by discharge into the surrounding medium, well-developed and 

 permanent anal pores occurring in some forms (see supra) . Many of 

 the products of assimilation are similarly disposed of by defecation. 



(6) Saprozoic Nutrition. — In holozoic nutrition the food sub- 

 stances are in the form of complex proteins, 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 disintegrating 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 in most cases at a special receptive area near 

 the base of the flagellum, as in Chilomonas yaramecium (Fig. 46, 

 p. 91). Many of the smaller types of flagellates obtain their nutri- 

 ment in this way, extracts or infusions of animal or plant tissues 

 containing various salts and organic compounds forming excellent 

 culture media for such Protozoa. Nothing 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. 



Very little advance has been made in the matter of saprozoic and 

 saprophytic nutrition. The general assumption, based upon the 

 thriving cultures in infusions of disintegrating animal and plant 

 matter, has been that dissolved proteins are taken into the proto- 

 plasmic bodies of many kinds of Protozoa by absorption through the 

 general cortex or through some specialized region for the purpose. 

 13 



