Certain Reactions of Biocolloids and Cell-masses. 77 



zinc salt, although very dilute, retards swelling noticeably, and exerts 

 a greater effect on the imbibition capacity than does either of the 

 other reagents named. 1 



Whatever value may attach to this procedure, it seems reasonable 

 to assume that salts less toxic in effect than those of zinc and identical 

 with those already present in the embryo-sac offer the greatest promise, 

 and their most intense effect might be secured when acidified. 



The presence of free amino-groups in the cell and their rapid penetra- 

 tion of plasmatic structures makes it highly probable that some of 

 these substances singly or in combination might diffuse throughout the 

 cytoplasmic structure of the embryo-sac and also reach the chromo- 

 somes with a high degree of possibility of affecting then* genetic con- 

 tent or potentiality. 



1 MacDougal and Spoehr. The effect of organic acids and their amino-compounds on the hydra- 

 tion of agar and on a biocolloid. Proc. Soc. Exper. Biol. and Med., 16:33. 1918. 



MacDougal, D. T. The experimental modification of germ-plasm. Annals Mo. Bot. Garden, 

 2:253-274, Feb.-Apr., 1915. 



