Fundamental Features of Phytocolloids. 25 



albumin, and some of the globulin, is dissolved in the water, which also 

 contains the salts of the bean. The effects of albumin were tested sepa- 

 rately, following the measurement of globulin effects, and the swellings 

 of thin plates of 9 parts agar and 1 part albumin were as follows : 



TABLE 7. 



p. ct. 



Distilled water 1 , 158 



Potassium nitrate, . 01 M 947 



Potassium nitrate, citric acid, 0.01 N 500 



Citric acid, 0.01 N 421 



Potassium nitrate, potassium hydroxid, 0.01M 421 



Potassium hydroxid, 0. 01 M 316 



The comparison of the above data with those obtained from the agar- 

 globulin reveals the fact that while the globulin does not appear to 

 increase the imbibition capacity of agar very much, the albumin does 

 exercise such positive effect, the mixture showing a capacity three 

 times as great as in acid or alkali. The swelling in acids is slightly 

 greater than in alkalies, in accordance with tl e action of other mixtures 

 of albumin. Imbibition by the globulin mixture in potassium nitrate is 

 relatively high compared to water-effects, while it scarcely rises above 

 that in acids. The swelling of the agar-albumin in this salt is more 

 than twice that of acidified and alkaline salts, acids, and alkalies. 



The presence of insoluble inclusions is of course the normal and usual 

 condition in the cells of plants during extended periods, and it was 

 desirable to ascertain whether or not material wholly neutral in biocol- 

 loidal plates would affect hydration. The first trial was made with a 

 cotton lace about 1 cm. in width and 0.5 mm. in thickness. This was 

 well softened, and when laid in the mold the warm colloidal mass was 

 poured over it, accomplishing an intimate penetration among the 

 smaller fibers of the threads. 



The portion of a plate of agar and oat protein free from the webbing 

 dried down to a thickness of 0.18 mm., and sections of this swelled 

 2,111 per cent in distilled water, while the increase in swamp water 

 was 1,277 per cent. Sections containing webbing swelled 1,583 per 

 cent in bog water and the same amount in distilled water, and 1,195 

 per cent in swamp water, calculated on the basis of the thickness of 

 biocolloid noted above. It is by jio means certain, however, that the 

 colloid does dry in equal mass on the webbing. (See Chapter VI for 

 discussion of bog water.) 



Calculated in terms of actual thickness, the swelling of the webbed 

 sections was 491 per cent in bog water and in distilled water, while it 

 was but 371 per cent in swamp water. The presence of the webbing 

 appears to diminish the proportion of swelling in distilled water and 

 bog water, but not that in swamp water. Swamp water (see p. 68) 

 contains an amount of calcium salts which notably affects swelling in 

 clear sections. This operated to mask any effect due to the presence 

 of the cotton fibers in colloidal sections. 



