56 CARNEGIE INSTITUTION OF WASHINGTON. 



containing 40 per cent or more carbohydrates swell most in amino- 

 compounds. Balanced biocolloids swell most in the presence of 

 hydroxyl ions. These reactions are parallel to those of living and dried 

 cell-masses of plants and follow through the seasonal variations 

 determined by chemical analyses. 



2. Biocolloids of which more than a fourth is carbohydrate are 

 highly sensitive to the action of hydrogen ions, which restrict hydration. 



3. The basic histidine and glycocoU (which is slightly on the acid 

 side of neutral) increase hydration in biocolloids containing more than 

 40 per cent carbohydrate. Maximum swellings of 4,300 per cent by a 

 mixture of 1 part agar and 3 parts gelatine in acid representing a high 

 concentration for plant juices, and of 3,930 per cent by a mixture of 2 

 parts agar and 3 of gelatine in histidine, are of great physiological 

 interest. But little information concerning the presence or action of 

 the basic amino-compounds in plants is available. 



4. GlycocoU and glycocoll ester increase the swelling of agar. Gly- 

 cocoU lessens swelling of gelatine, while glycocoll ester, glycocoll-ester 

 hydrochloride, and glycocoll-hydrochloride increase it beyond that 

 shown in distilled water. 



5. The hydroxides of the strong metallic bases limit the hydration 

 of agar according to their position in the electromotive series, the least 

 swelling taking place under the action of the strongest base at con- 

 centrations of O.OIN with the apparent exception of rubidium. Begin- 

 ning with the strongest, the series runs K, (Rb), Na, Li. 



6. The various effects of barium, calcium, and strontium are not so 

 clearly determined, and the quantitative relations of these metals 

 are not known definitely. Hydration values of agar at O.OIN were 

 Sr(0H)2 — 815, Ca(OH)o — 860, Ba(0H)2 — 900. 



7. Hydration of agar in calcium hydroxide exceeds that in water at 

 O.OOOIN. Increase of hydration beyond that of water by dilute 

 solutions of hydroxides of calcium, potassium, rubidium, potassium, 

 sodium, and lithium is an effect we have hitherto ascribed to amino- 

 compounds only. Excess values for aniline and ammonium hydroxide 

 are given. 



8. The incorporation of bases in agar lessens its hydration capacity 

 in any concentration yet tested, and this is also true of biocolloids of 

 which carbohydrates constitute more than half. In mixtures con- 

 taining more gelatine, hydration capacity in acids and in hydroxides 

 may be increased by included bases. The inclusion of a metaUic 

 base and its presentation in a hydrating solution would give different 

 results in a colloidal or plasmatic body, such as a nucleus or chromo- 

 some. 



9. The data in this article were secured chiefly by the swelling of 

 trios of sections with a total volume of 4 to 8 cubic millimeters under 

 the auxograph in dishes into which 25 to 30 c. c. of solution were put 



