SCIENTIFIC PROCEEDINGS 



Abstracts of Communications. 

 Ninety-fifth meeting. 



Rockefeller Institute for Medical Research, December 18, igi8. 

 President Gies in the chair. 



21 (1396) 



The effect of organic acids and their amido-compounds on the 

 hydration of agar and on a biocolloid. 



By D. T. MacDougal and H. A. Spoehr. 



[From the Desert Laboratory, Tucson, Arizona.] 



Earlier researches on hydration effects were concerned chiefly 

 with gelatine as taken to represent the action of living matter. 

 The effort to obtain results directly applicable to plant protoplasm, 

 led to a consideration of chemical composition, solubility and other 

 properties as a consequence of which mixtures of agar and protein 

 were found to give hydration reactions so nearly comparable to 

 those of living cell-masses that their study yields extremely useful 

 facts and numerous stimulating suggestions. 



The importance of the acids or of the hydrogen ion concentra- 

 tion in swelling had become apparent very early in the brief history 

 of this subject. Workers using botanical material have dealt 

 with this matter chiefly by the use of hydrochloric, and with 

 acetic, citric and malic acids, and with salts of biological occur- 

 rence and concentrations. Although much careful work has been 

 done some doubt still exists as to the part which the acid radicle 

 may play in the complex system of substances always present in 

 the protoplasmic colloid. A study of the action of these acids and 

 of organic acids and of their amido compounds promised com- 

 parisons that might be of importance in this matter, and a series 

 of measurements were carried out in the equable temperature 

 chambers of the Coastal Laboratory August to November, 191 8. 



33 



