40 



Hydration and Growth. 



Table 21. 



Calcium nitrate. 



The range of concentrations examined does not exhaust the possi- 

 bilities. It has been previously found that biocoUoids will take up 

 some water and swell from the most concentrated mixtures of salts. 

 On the other hand, the greatest attenuations exerted some influence 

 on the water capacity, although it may be surmised that at a lower 

 concentration the deviation on the swelling in the salt solution from 

 that in distilled water would be so slight as to be negligible in all 

 biological applications of the facts. Living matter is at all times 

 impregnated with salts to a degree within the range of these tests. 



In the continuance of the series to test the 

 effects of some of the salts of biological im- 

 portance, plates of agar and oat protein 0.2 

 mm. in thickness were swelled at 15° C. in cal- 

 cium nitrate. Two series of measurements are 

 shown in table 21. 



The weakest attenuation used allows a swell- 

 ing practically equivalent to that of distilled 

 water. Two series of greatest divergence 

 from the effects of potassium nitrate are to be found in dilutions of 

 0.02 M, while distinctly different action is seen to prevail in the con- 

 centrated solutions above the unimolecular. 



The sections of agar-oat protein used for testiog the effects of cal- 

 cium chloride were 0.16 mm. in thickness and the swelling was made 

 at the same temperature as in potassium nitrate, 15° C. The measure- 

 ments in 24 hours are given in table 22. 



Table 22. Table 23. 



2 M 



0.2 M... 



.02 M.. 



.002 M. 



.0002 M 



p. ct. 



975 



525 



650 



1,425 



1,975 



p. ct. 

 917 

 722 

 778 



1,556 



The chloride of calcium appears to limit swelling to a greater 

 extent than the nitrate, so far as table 22 is comparable with that 

 obtained from swelling in the nitrate. 



The next trial was made with potassium chloride in solutions of the 

 same concentration as above. Agar-oat protein was used and the 

 swellings at 15° C. in 24 hours are given in table 23. 



The amount of imbibition in potassium chloride is greater than that 

 in calcium chloride in equivalent concentrations, while it is noticeable 



