SCIENTIFIC PROCEEDINGS. 



Abstracts of Communications. 

 One hundred nineteenth meeting. 



Rockefeller Institute for Medical Research, December 21, IQ21. 

 President Wallace in the chair. 



52 (1799) 



The distentive agencies in the growth of the cell. 



By D. T. MACDOUGAL. 



[From the Desert Laboratory, Tucson, Arizona.] 



The newly separated vegetative cell including that of the 

 simpler animals such as the Protozoans is a minute mass of 

 protoplasm in which there are at first no lacunae or breaks of 

 any size, and the externally bounding layer is of extreme thinness 

 and tenuity. The enlargement of expansion of the protoplast in 

 this stage is chiefly one of formation or accretion of additional 

 colloidal material and its hydration to a point where the water 

 content is 50 to 500 times that of the dry weight of the included 

 material. 



My experiments of the last five years show that substances 

 known to accelerate or facilitate growth also carry the hydration 

 of living and dead cell masses and of pentosan-protein colloidal 

 masses to a point beyond that which may occur in pure water. 

 Such amino compounds, acidic and basic, as asparagin, alanin, 

 glycocoll, phenyl-alanin and histidin, hydroxides and chlorides of 

 potassium, sodium, magnesium and calcium in * concentrations 

 from 0.001 M. to 0.000,01 M. hydrochloric acid in the same range 

 and water-soluble B yeast-vitamine Harris are included in the 

 list and these are concentrations of biological occurrence. The 

 enlargement of the cell in this stage must be due directly to 

 imbibition and swelling as the vacuoles are not yet formed, 



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