Distentive Agencies in Growth of Cell. 107 



steps be moved up to where it shows a tonicity equivalent to 

 0.005 M. This is a short series of small steps, but it is one shown 

 by a cell in a static condition in the sense that none of its parts 

 are being renewed or altered by metabolism, but most important 

 of all it is in the direction of cumulative turgidity. Such action 

 may or may not however imply any accumulation of electrolytes 

 but it is proven that the cell contents by changes in material 

 partly or entirely derived from the jelly or plasma shows an in- 

 creasing osmotic pressure measured against potassium chloride. 

 The actual diffusion of the salt into the vacuole has not been 

 measured. 



It is the external zone or phase boundary of the plasmatic 

 layer to which attention has been chiefly directed in studies of 

 permeability and diffusion of salts into and out of the cell. Its 

 original structure at the moment of formation of the new cell is 

 in all probability that which might be predicated for the external 

 layer of any such a semi-liquid mass of jelly, composed of albumens, 

 pentosans, soaps and lipoids, the two last-named forming but a 

 small proportion of the dry weight of the mass, but by their surface 

 tension relations would tend to assume a peripheral position. 

 Following this initial arrangement it is also to be seen that com- 

 pounds of these groups would continue to be added from the 

 products of a continuing metabolism. The resulting formation 

 would present a picture widely different from that of the parch- 

 ment membrane to which it has been so often compared. In 

 accordance with this view the shrinkage of the protoplasm from 

 the wall in plasmolysis is not accompanied by a detachment of a 

 membrane from the wall but by an actual rupture or partial 

 destruction of the peripheral layer. When in addition my own 

 results to the effect that the hydration or swelling of dried sections 

 of biocolloids is accelerated by balanced solutions of sodium, 

 while the osmotic action of artificial cells lined with the same 

 biocolloids is seen to be not affected by antagonisms, a revision of 

 some widely prevalent views as to the nature of permeability 

 seems to be required. 



If we now turn attention to the outer wall of the vegetable 

 cell we see it developing from a semi-liquid cell-plate to a condition 

 approaching that of densely layered and infiltrated structure; 



