22 MACDOUGAL— ACTION OF BASES AND SALTS 



take into account the compounds of the fatty acids with the com- 

 mon bases, the soaps which as McBain and Salmon have recently 

 shown may exist as both electrolytes and colloids in colloidal masses.'^ 



These soaps are an almost inevitable component of protoplasm, 

 and some studies of their possible action in the cell will be taken up 

 in a paper now in preparation. Preliminary to any profitable con- 

 sideration of the soaps it is necessary to have some definition of the 

 parts which salts may play in the biocolloidal machine. The meas- 

 urements of swellings given in earlier papers showed that the in- 

 corporation of nutritive salts in colloidal masses lessened the hydra- 

 iton capacity. It is now apparent from the results given on the 

 following pages that such restrictive action was due to the high 

 concentrations employed. This however cannot be said of the 

 amino-compounds, which used as hydrating solutions accelerated 

 swellings, but which incorporated in colloidal masses uniformly 

 reduced hydration capacity in whatever concentration used. 



In the tests which are to be described it was planned to include 

 the salts which are of importance in nutrition, which induce accel- 

 erated swelling in agar and agar-gelatine mixtures in implied con- 

 centrations, the calcium and sodium furthermore being used in ap- 

 proximately balancing proportions. These salts were first used with 

 purified agar and hydration values as in Table VI were obtained. 



TABLE VL 



Hydration of Agar and Salts in Salt Solutions. 

 5 g. agar, loo c.c. KCl o.ooi^l/, 60 c.c. NaCl at o.oooiM, and 10 c.c. CaCl 

 at o.oooiil/. Sections 0.2 mm. to 0.27 mm. in thickness swelled at 14° C. 



Th. Vol. 



KCl o.oooiil/ 2,220 2,780 



NaCl o.oooiM 1,800 



MgCU o.oooiM 1,380 



CaCls o.oooiA/ 1,400 



HCl o.oooiiV 2,230 



Salt solution as above 2,600 



Water 1,760 



The total swelling in the present instance is one which is equiva- 

 lent to that shown by many preparations including that of agar 

 "Jour. Amcr. CJieiii. Soc, 42: 426, 1920. 



