Guilliermond - Atkinson — 28 — Cytoplasm 



Water:- Water is an important constituent of protoplasm. In 

 fact, all protoplasm contains water interposed between its micelles. 

 This water is indispensable for the manifestations of vital phe- 

 nomena as these can be produced only if the protoplasm is in a 

 semi-fluid state. The water content of living substance varies 

 with age, i.e., according to the physiological state of the cells and 

 also, in certain plants, according to the environmental conditions. 



In a general way, in the course of the life of a plant, the maximum 

 water content coincides with the maximum physiological activity. 

 The differences which exist in the viscosity of the cytoplasm, vary- 

 ing with the age of the cells, have already been mentioned. The 

 amount of water held in the cytoplasm varies from 80-90% by 

 weight. A part of this water may be removed but then the vital 

 activity is diminished. If it is almost all suppressed, the proto- 

 plasm in certain cases may not die but passes into a state of re- 

 tarded activity (anhydrobiosis) . This is the case normally in the 

 spores of bacteria and fungi, as well as in the seeds of phanero- 

 gams which, during maturation, become dehydrated until they con- 

 tain only 10-18% of water and sometimes, as in certain fatty 

 seeds, as little as 5-6%. 



