PHYSIOLOGY 101 



cepting Ciliophora, is the so-called volutin or metachromatic gran- 

 ule. It is apparently equally widely present in Protophyta. In fact 

 it was first discovered in the protophytan Spirillum volutans. Meyer 

 coined the name and held it to be made up of a nucleic acid. It stains 

 deeply with nuclear dyes. Reichenow (1909) demonstrated that if 

 Haematococcus pluvialis (Fig. 40) is cultivated in a phosphorus-free 

 medium the volutin is quickly used up and does not reappear. If 

 however, the organisms are cultivated in a medium rich in phos- 

 phorus, the volutin increases greatly in volume and, as the culture 

 becomes old, it gradually breaks down. In Polytomella agilis (Fig. 

 98, c, d), Doflein showed that an addition of sodium phosphate re- 

 sulted in an increase of volutin. Reichenow, Schumacher, and others, 

 hold that the volutin appears to be a free nucleic acid, and is a spe- 

 cial reserve food material for the nuclear substance. Recently Sas- 



FiG. 40. Haematococcus pluvialis, showing the development of volutin 

 in the medium rich in phosphorus and its disintegration in an exhausted 

 medium, X570 (Reichenow). a, second day; b, third day; c, fourth day; 

 d, e, sixth day; f, eighth day. 



suchin (1935) studied the volutin in Spirillum volutans and Sarcina 

 flava and found that the volutin appears during the period of strong 

 growth, nourishment and multiplication, disappears in unfavorable 

 condition of nourishment and gives a series of characteristic carbo- 

 hydrate reactions. Sassuchin considers that the volutin is not related 

 to the nucleus, but is a reserve food material of the cell, and is 

 composed of glycoprotein. 



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 involved 

 in this process appears to be brought into contact with the sub- 

 stances in two ways in Protozoa. The great majority of free-living, 

 and certain parasitic 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 



