138 THE ROYAL SOCIETY OF CANADA 



relation to concentration within the limits used (N/20 to N/1280). To 

 be noted however is the fact that ammonium chloride represses swelling 

 more than sodium acetate, contrary to Hofmeister's finding.^ 



The effect of alkalis. At the higher concentrations the effect of 

 alkalis (potassium hydroxide, ammonium hydroxide) is similar to but 

 quantitatively less than that of acids on the rates of swelling, the 

 maximum occurring at first at N/20 and later (30 minutes) in N/80. 

 The minimum rates however are at first as great as in water, soon 

 overtaking them. The presence of a salt (ammonium chloride with 

 ammonium hydroxide; potassium nitrate with potassium hydroxide, 

 in equal amount of equal concentrations) depresses the rates at 

 the lower concentrations (N/640 to N/2560) to less than that in 

 water (temp. K) for a while, though the total swelling at these con- 

 centrations is greater than in water. There is, it would seem, a rather 

 distinct similarity in the response of gelatine to ^cids and alkalis, and 

 my observations give colour to the expectation expressed by Proctor 

 and Wilson in the words "It is probable that the laws governing 

 alkali swelling are the same as those governing acid-swelling. "- 



Aside from the bearing of the above experimental results on our 

 general understanding of the behaviour of emulsoids, they afford a 

 basis for some expectation regarding the behaviour of protoplasm. 

 This is in part realized. Thus, the ability of acids to cause increased 

 growth rates referable in part to imbibition pressure, at such high 

 concentration as 40% cane sugar, while the protoplasts burst at lower 

 concentrations, compared with the behaviour toward alkali, harmonise 

 with the fact that acids cause greater swelling of gelatine than alkalis. 

 Just as there is a concentration of acid or alkali which causes maximum 

 swelling, less swelling occurring in concentrations both above and 

 below said concentration, so in the case of protoplasm, a maximum 

 growth rate occurs at a certain concentration of acid or alkali, the 

 rates being less at concentrations both above and below. 



The effect of acids and alkalis in causing growth is however seen 

 at much lower concentrations than those which can cause observable 

 swelling of gelatine. Indeed the effective concentrations of acids are 

 within the range which cause repression of swelling of gelatine, a re- 

 pression which could only be emphasized by any salts which are 

 present in the protoplasts. There is evidence, if not yet conclusive, 

 that a repression of swelling of gelatine occurs at low concentrations 



'Arch. exp. Phys. Path. 27: 395, 1890 (through Taylor, W. VV. The Chemistry 

 of Colloids, N.Y. 1915.) 



^In this connection see the important results of Proctor, H. J. and Wilson, J. A. 

 The Acid-gelatine equilibrium, Jour. Chem. Soc. London, 109-110 307. Ap. 1916. 



