>] DESICCATION AND PROTOPLASMIC FUNCTIONS 59 



These determinations suffice to show that water immensely 

 predominates over any other substance in active organisms, 

 and indicate that it plays an important role. 



The role played by water is, in fact, extremely varied. It 

 serves to maintain that unstable, foam-like structure of the 

 protoplasm upon which its capacity for movement depends ; it 

 acts as a solvent for matter taken into the protoplasmic body; 

 and it serves to transport dissolved substances from place to 

 place in the organism. In a word, it is essential to movement 

 and to those chemical processes which constitute metabolism. 



2. Ox THE EFFECT OF DESICCATION UPON THE FUNC- 

 TIONS OF PROTOPLASM 



We may consider this topic under the following heads : 

 (1) effect upon metabolism ; (2) effect upon the motion of 

 protoplasm; and (3) the production of desiccation-rigor and 

 death. 



1. Effect of Dryness on Metabolism. Since water is so 

 essential to metabolism, we should expect that a diminution of 

 metabolism would accompany dryness. And this is clearly the 

 case. Thus dry seeds, in which the water is reduced to only 10 



