Constituents of Biocolloids Affecting Hydration and Growth. 35 



action of an ordinary revolving egg-beater. The albumin-lanolin 

 mixture was now added to the agar and it was stirred vigorously some 

 time above 35 C., and when it had come down to 33 C. it was cast in 

 two portions. One was on filter-paper which was stretched in the 

 usual manner, and the other smaller lot on a glass plate. The mixture 

 set in a few minutes, the room temperature being about 20 C. The 

 plates as above came down to an average thickness of 0.2 mm., which 

 were tested at a temperature of 18 C., swelling 2,100 per cent in dis- 

 tilled water and but 1,750 per cent in 0.01 M asparagine. 



A conception of living matter as simply a two-phase colloid in which 

 the main elements are distributed between the more liquid and the 

 denser phases simply according to their physical properties may be 

 sufficient to interpret certain general reactions, but one does not pro- 

 ceed very far with the actual mechanics of living matter until it is 

 realized that specializations of various kinds come in. Attention has 

 already been called to the varying proportion of proteins and their 

 probable effect on hydration. According to Kite, 1 the vacuolar fluid 

 of Spirogyra contains some proteins in a dissolved or disperse state, 

 and this fluid is even higher in nitrogenous material in Char a. A 

 doubtful amount of plasmatic material may be taken to be hi a dis- 

 perse condition in plants under ordinary conditions, and the heavier 

 portions differ widely as to density or viscosity, the outer layer of the 

 nucleus and of the cell being a gel of greater rigidity than the interior 

 portions. The fact that "none of the cytoplasm goes into solution 

 very readily even when cut into very minute pieces," as described by 

 Kite with respect to Spirogyra, can not be taken to prove that pro- 

 toplasm may not readily go into the disperse or liquid phase in the 

 fluids of the cell. The pentosans may move slowly, but during the 

 growth of the nucleus, water and other substances pass into it from the 

 surrounding cytoplasm. Again, at other times, material may be seen 

 to pass from the nucleus to the cytoplasm. Many of these phenomena 

 may now be explained on known behavior of colloids, and the study 

 of colloidal action promises to yield much additional information upon 

 the movement and interaction of the parts of the protoplast. 



Most of the variations in composition mentioned are illustrated in 

 the structure of a single cell, and in the growth and development of 

 these units the accumulation, migration, and disintegration of these 

 substances may be definitely connected with the more important 

 movements in the cell. The localization of salts is a matter which 

 has been dealt with at great length by MacCallum, and the results 

 which he has secured with a few of the more important salts afford a 

 basis for some conception of the heterogeneity of the cell with regard 

 to this feature. 



1 Kite, G. L. The physical properties of protoplasm of certain plant and animal cells. Amer. 

 Jour, of Physiol., 32 : 146, especially pp. 161 and 162. 1913. See also Conklin, E. G. Effects 

 of centrifugal force on the structure and development of the eggs of Crepidula. Jour. Exper. 

 Zool., 22: Feb. 1917. See pp. 356-364. 



