96 



PROTOZOOLOGY 



cleic acid. It stains deeply with nuclear dyes. Reichenow (1909) 

 demonstrated that if Haematococais pluvialis (Fig. 38) was culti- 

 vated in phosphorus-free medium the volutin is quickly used up 

 and does not reappear. If however, the organisms are cultivated 

 in a medium rich in phosphorus, the volutin increases greatly in 

 volume and, as the culture becomes old, it gradually breaks down. 

 In Polytomella agilis (Fig. 92, c, r/), Doflein showed that an addi- 

 tion of sodium phosphate resulted in an increase of volutin. 

 Reichenow, Schumacher, and others, hold that the volutin appears 



Fig. 38. Haematococcus phivialis, showing the development of volu- 

 tin in the medium rich in phosphorus and its disintegration in ex- 

 hausted medium, X570 (Reichenow). a, second daj^; b, third day; c, 

 fourth da}'; d, e, sixth day; f, eighth day. 



to be a free nucleic acid, and is a special reserve food material for 

 the nuclear substance. Recently Sassuchin (1935) studied the 

 volutin in Spirillu?n volutans and Sarcina flava and found that the 

 volutin appears during the period of strong growth, nourishment 

 and multiplication, disappears in unfavorable condition of nour- 

 ishment and gives a series of characteristic carbohydrate reac- 

 tions. Sassuchin considers that the volutin is not related to the 

 nucleus, but is reserve food material of the cell, which is compos- 

 ed of glykoproteid. 



Respiration 



In order to carry on various vital activities, the Protozoa, like 

 all other organisms, must transform the potential energy stored 

 in highly complex chemical compounds present in the cytoplasm, 

 into various forms of active energy by oxidation. The oxygen in- 

 volved in this process appears to be brought into contact with the 

 substances in two ways in Protozoa. The great majority of free- 

 living, epizoic and certain endozoic forms absorb free molecular 

 oxygen from the surrounding media. The absorption of oxygen 

 appears to be carried on by the permeable body surface, since 

 there is no special organella for this purpose. The polysaprobic 

 Protozoa are known to live in water containing no free oxygen. 



