CHAPTEK II 



ABSORPTION AND TRANSMISSION OF WATER 



I. ABSORPTION OF WATEK 



As HAS been seen in the previous chapter, it is absolutely 

 essential that every living mass of protoplasm be saturated 

 with water. This is so primarily on account of the fact that 

 the energy_jtransformations which are designated as vital 

 phenomena occur solely in aqueous solutions. It is also 

 true because of the fact that water is actually used in these 

 transformations ; it is chemically combined with other sub- 

 stances to form carbohydrates, proteids, etc. Therefore it 

 becomes necessary that every active cell be not only satu- 

 rated with water, but also that it be in connection with an 

 external supply of this material. Especially is this so where 

 water is lost by evaporation. It is possible, of course, for a 

 plant cell to become hermetically sealed within a water-proof 

 wall (e. g., fungus spores, etc.), but as long as it is active 

 and growing it cannot be so shut ofp from the outward sup- 

 ply of water. 



If the cell be naked and immersed in water, the supply 

 of this substance is always at hand and simply diffuses into 

 the protoplasm as it is used in metabolism. If the organ- 

 ism be in contact with a moist substratum throughout most 

 of its surface, as is the Myxomycete plasmodium, the 

 absorption of water takes place from the imbibed water of 

 the substratum. When the cells are surrounded by cellu- 

 lose membranes, these are kept saturated by diffusion from 

 without, and the protoplasm absorbs its needed water from 

 them. The cellulose walls of ordinary cells act like the 

 porous and imbibed substratum against which the Myxomy- 



91 



