Effect of Certain Organic Acids and Amino Compounds. 61 



TABLE 50. p. ct. 



Distilled water 923 



Glycocoll 3 M 800 



Glycocoll 0.05 M 654 



Glycocoll 0.01 M 600 



Here again the uneven dispersion of the mucilage results in auxo- 

 graphic records, the obvious meaning of which would be unsafe to 

 follow. It is highly probable that the high relative swelling in the 

 concentrated solution is due to coagulatory or aggregation effects, 

 especially on the surfaces of the sections, resulting in a sac-like con- 

 dition which would show considerable increase before dispersion 

 began, resulting in a final shrinkage. This dispersion began earlier 

 in the weaker solutions. 



Swellings of gelatine in glycocoll ran uniformly low, the presence of 

 this substance apparently accelerating solution of the gel. 



Sections consisting of 4 parts agar and 1 of gelatine which had an 

 average thickness of 0.3 mm. swelled as follows at 15 C. in glycocoll: 



TABLE 51. p. ct. 



Glycocoll, 0.3M 1,550 



Glycocoll, 0.05 M 1,233 



Glycocoll, 0.01 M 1,960 



Glycocoll, 0.002M 1,767 



The average swelling of such sections in water was about 1,700 per 

 cent and the irregularity characteristic of auxographic measurements 

 of the action of this amino-acid is seen in the above results. 



A preparation was now made in which 2 parts of the water-soluble 

 protein from oats was added to 8 parts of agar in a 2.5 per cent solution 

 of the latter. The plates dried to a thickness of 0.25 mm. When 

 sections of such biocolloids were swelled in the glycocoll series, the 

 results were as shown in table 45, the hydration in concentrations less 

 than 0.01 M approaching and surpassing those in distilled water. 



A number of tests were made to determine the influence of glycocoll 

 on hydrations in acetic acid. The first was that of surface slices of 

 Opuntia, which had dried to a thickness of 0.8 mm. Trios swelled 163 

 per cent in 0.05 N acetic acid and 156 per cent in a 0.05 N solution 

 of acetic acid and glycocoll each. No especial significance can be 

 attached to the lesser swelling in the double solution, except that no 

 evidence as to acceleration of swelling by the addition of the amino-acid 

 was obtained. 



Next, trios of sections of 8 parts agar and 2 parts gelatine 0.3 mm. in 

 thickness were swelled in the acetic and amino-acetic solutions 0.01 N 

 at 18C. The swelling in the acetic acid alone was 1,450 per cent, 

 while that in the combined solutions was but 1,300 per cent, which 

 agreed with the previous effects in being less than in the acid alone. 

 It is to be noted that the amount of the acetic acid in the combined 

 solution in the swelling-dish would be but half that when this acid was 

 used alone. 



