16 MACDOUGAL— ACTION OF BASES AND SALTS 



A preliminary announcement of the fact that excessive hydra- 

 tion vakies in agar and biocolloids were obtained when these sub- 

 stances were swelled in dilute salt solutions was made before the 

 Physiological Section of the Botanical Society of America at Chi- 

 cago, December 28, 1920, which is in press in the American Journal 

 of Botany for June, 1921. Also of interest in this connection is the 

 announcement of Loeb of the reversals of specific effects of salts 

 above and below M/16 on the swelling, osmotic pressure, and vis- 

 cosity of gelatine.^ 



S. C. J. Jochems measured the effects of a number of acids, bases 

 and salts upon stems of Laminaria, Fucus, agar, carrageen and upon 

 a number of seeds in 1919. The wealth of results include a num- 

 ber of important generalizations as to the behavior of the plant 

 mucilages and organs when swelled in a number of solutions with a 

 wide range of concentrations. 



Jochems found that no rule could be formulated for the influ- 

 ence of the basicity of the acid radicals in the sweUing of agar and 

 that the eft'ect of the valency of the base was very small. Still more 

 surprising is the conclusion reached by Jochems that while nearly 

 all of the salts tested, NaCl, NaBr, Nal, NaNo,, Na.So,, Na,HPO„ 

 CaClo, lessened swelling at o.oi M, at 0.05 M the imbibition was 

 greater than in water. The agar was commercial material and some 

 of the diff'erences between these conclusions and the facts discussed 

 in the present paper are to be attributed in part to my use of a spe- 

 cially purified agar.* 



My own experiments were planned to test the action of salts of 

 interest in connection with nutritive solutions within the range of 

 biological interest, which would lie between o.oi M and o.oooi M. 

 Single series of swellings in KOH and HCl were included for pur- 

 poses of comparison. 



The first series of tests were made with two plates of agar a year 

 old. Plate A swelled 1,800 per cent, in thickness and 3 to 4 per 

 cent, in length when freshly made, and Plate B, 3,000 per cent, in 



^ Loeb, J., " The Action of Salts in Low Concentration," Jour. Gen. 

 Physiol., 3: 391-414, 1921. 



* Jochems, S. C. J., " De imbibite van plantaardige celwanden in oplos- 

 singen van electrolyten." Published by A. H. Kruyt, Amsterdam, 1919. See 

 pages 35-46. 



