48 



Hydration and Growth. 

 TABLE 39. 



The relative swellings of the biocolloid without the culture salts 

 presents the general features of such mixtures, being highest in dis- 

 tilled water, next in potassium nitrate, less in acidified potassium 

 nitrate, less in citric acid, and varying in the relations of the hydroxid 

 and the alkaline salts. 



The plates in which the culture salts were incorporated showed 

 relative swellings which did not differ widely from the expectancy, 

 except in the swelling in alkali and alkaline salts. The addition of the 

 dextrose could not be seen to exert any definite action. The outstand- 

 ing fact is the general retarding effect of salinity on the hydration 

 capacity, a fact of possible enormous importance in the organism. 



A mixture including 4 parts of agar, 5 parts of gum arabic, and 1 

 part of gelatine was made and sufficient potassium chloride was added 

 to make it 0.01 M of this compound. Swellings at 18 to 20 C. were 

 as given in table 40. 



TABLE 40. p. ct. 



Distilled water 612 



Citric acid, 0.01 N 465 



Sodium hydroxid, 0.01 M 214 



Hydrochloric acid 0.01 M 535 



Hydrochloric acid, potassium chloride, 0.01 M 419 



A general restriction of nearly all of the swelling reactions is illus- 

 trated by the measurements in table 40, while the relative increase in 

 acids is high. 



As a further combination of two forms of carbohydrate, albumen, 

 amino-acids, and of the salts which are found in plants, a mixture was 

 made which contained the following material: 



TABLE 41. 



Agar . . , 

 Acacia. 



6 

 2 



Gelatine 1 



Albumin (Phaseolus) 1 



Potassium nitrate . 0058 



Potassic phosphate, dibasic 0185 



Magnesium sulphate (7H 2 O) 0418 



Calcium nitrate (4H 2 O) 0398 



Total colloid material 10 



Total nutrient salts. . .0105 



