20 



MACDOUGAL— ACTION OF BASES AND SALTS 



in water alone. The swelling in KCl at o.oooi M with a PH value 

 of 5.7 is not much greater than in water, and the accelerating effect 

 does not rise so rapidly as in the acid solution, the swelling at o.ooi 

 M with a PH value of 5.8 being not much more than double that in 

 water. Still another effect of interest is that of the calcium chloride 

 solutions, which induce a maximum sv/elling at o.ooi M but de- 

 press hydration as the concentration rises, and as it falls away from 

 this point. 



TABLE in. 



o.oi M. 



Th. 



Vol 



Th. 



Vol. 



0.0001 M. 



Th. 



Vol. 



KCl 



CaCl 



HCl 



Salt solution (see p, ii) 

 Water 



1,400 



1,596 



2,200 



640 

 830 



730 

 780 



1,160 

 1,000 

 1.080 

 1,300 

 910 



The chief interest in all of the foregoing results lies in their pos- 

 sible use in interpretation of the action of living matter. Varied 

 and extensive series of tests have proved that mixtures of pentosans 

 or mucilages and of albumin or gelatine formed a biocolloid in 

 which many of the reactions of living and dead cell-masses to hydra- 

 tion agencies might be exemplified. It was therefore believed to be 

 of importance that the action of salts upon these mixtures should 

 be tested in connection with a measurement of their action upon liv- 

 ing material. As has been discussed in many previous papers the 

 behavior of a biocolloid to a hydrating solution depends in many 

 important features upon the proportions of the two main constitu- 

 ents. The action of salts was therefore tested upon two types of 

 biocolloids, one in which the pentosan agar formed the greater pro- 

 portion and another in which gelatine was the dominant component. 

 The swelling increases of two such mixtures are given in Table IV. 



It is notable that in the agar-gelatine mixture the eft'ect of the 

 potassium chloride is essentially identical with that produced on 

 agar alone, except that the limiting effect at the higher concentra- 

 tion is less marked, being at o.oi M but little short of the swelling 

 in water. Sensitiveness to hydrogen ion concentration as shown 

 in reactions to the acid was much more marked than in the agrar 



