DEPARTMENT OF BOTANICAL RESEARCH. 59 



substances and depress that of the pentosans. Bases or cations exert 

 a reverse effect on the albuminous substances and depress hydration 

 of the pentosans sUghtly. Certain amino-compounds depress the 

 swelHng of albuminous compounds, but facilitate the hydration of 

 pentosans, and dried sections of pentosan-albumin mixtures undergo 

 hydration in solutions of these substances to a degree equivalent to or 

 even greater than that in water. 



As to the second phase of growth, that of the incorporation of mole- 

 cules of sohd matter, it is ob\4ous that the mass of living matter may 

 not be increased simply by the addition or diffusion of sugars into the 

 mesh-work, as is supposed by some writers. 



Before the material in these carbohydrates may actually become a 

 part of the colloidal living mesh, it is undoubtedly broken down to 

 some extent by enzymatic or respiratory action, part of the material 

 being carried through transformations to organic acids or carbon 

 dioxide; some of the material is combined with the ammonia group 

 (NH2) to form amino-compounds, some with the lipins, while some 

 of these sugars may be converted to the pentosan form, in which they 

 would so markedly affect the hydration capacity of the mass. 



Protoplasm might be regarded as the wick of a lamp which draws 

 sugar into its meshes, burns the sugar, and in the burning some of the 

 sugar not completely consumed unites with other substances to form 

 additional fibers of the wick, of which the pentosans or mucilages are 

 examples. 



The so-called ''nutrient salts," in fact, yield no energy and furnish 

 no building-material. They may act as catalyzers or as releasing 

 agents, and as controls of water absorption or as guides in colloidal 

 arrangement, but they are not "food-material" in any sense. 



The enlargement of the individual masses of living cells in organisms 

 entails a certain amount of work which in the earlier stages is derived 

 almost entirely from imbibition or absorption, and while such action 

 continues throughout the growth or life of the living matter, there is in 

 addition the stretching action exerted by the expanding vacuoles by 

 osmotic action. The growing regions of plants at all times include 

 cells in all of these stages, from the newly separated protoplasm which 

 is expanding entirely by imbibition of water and incorporation of new 

 material, others in which the syneretically formed vacuoles are increas- 

 ing and thus adding to the volume of the cell by osmotic action, and 

 others approaching maturity, in which the vacuole may have attained 

 such size as to occupy many times the space of the hving matter, which 

 may indeed now be but a sac with its layers of irregular thickness lying 

 internal to the wall, which now has become dense and rigid. 



Growth in plants is therefore a hydration expansion or swelling of a 

 mass of pentosan-protein colloid or jelly which forms a sac or inclosing 

 layer of greater density, which takes in water and solutions by adsorp- 



