DEPARTMENT OF BOTANICAL RESEARCH. 55 



hydration capacity is increased above tliat in pure water. Mucilages 

 derived from various sources show some differences in reactions to the 

 solutions named while conforming to the generalizations given. Their 

 hydration is but little affected by the presence of the common sugars in 

 the water of suspension or dispersion. 



10. The albumins and their derivatives are amphoteric, being 

 capable of dissociating as acids or as bases. Hydration in the presence 

 of hydrogen ions may be much greater than in water and may reach the 

 possible maximum, while that in the presence of hydroxyl ions and of 

 various cations may also be in excess of that in water. Gelatine, as an 

 example of this group, shows such behavior, but has restricted hydra- 

 tion capacity in amino-acids, such as glycocoll. On the other hand, 

 the swelling is proportional to the high hydrogen-ion concentration of 

 such amino-acids as aspartic acid, which is dibasic. 



11. Variations in the hydration total or volume may be ascribed to 

 changes in the colloidal components of a plasma, to products of the 

 resident metabolism, to the action of substances absorbed during 

 hydration, or to fluctuations in temperature. 



12. The changes in volume of a mass of colloidal material are usually 

 not iso-diametrical during hydration. Such alterations are determined 

 by the structure of the jelly, which may be so differentiated as to show 

 expansion and contraction almost wholly along one axis. 



13. The analysis of the implied facts has also demonstrated that 

 growth is so essentially as to its nature and so largely as to volume a 

 matter of hydration that the compounds which facilitate the swelling 

 of phytocolloids and of cell-masses also facilitate or accelerate growth. 



Our more recent researches have led to the consideration of the follow- 

 ing subjects: (1) the proportions of carbohydrate and albuminous 

 matter in a colloid of the highest hydration capacity ; (2) the substances 

 or ions of biological significance which would raise the hydration 

 capacity of these phytocolloids to the highest limit ; (3) measurement 

 of the relative effects of some metallic bases upon a carbohydrate 

 colloid; and (4) determination of the amplitude and continuance of 

 alternating or repeated effects of renewed or replaced solutions. 



The results of the extensive auxographic measurements furnish a 

 basis for the summarized statements as below : 



1. By the use of the pentosan, agar, as representing the acid carbo- 

 hydrate and of gelatine for the amphoteric albuminous component, 

 trials were made to ascertain what proportions of these substances 

 would show hydration capacities of a range comparable to that of 

 living matter. A mixture containing one part carbohydrate and three 

 parts albuminous matter shows the highest general hydration capacity 

 under the influence of hydrogen, hydroxyl ions, and the ions which 

 may be derived from amino-acids. Biocolioids high in albuminous 

 matter swell most under the action of the hydrogen ion. Biocolioids 



