148 



Scientific Proceedings (76). 



the cotton-seed proteins are notably deficient for the purposes of 

 nutrition, we have conducted feeding experiments on rats in which 

 these proteins furnished practically all of the food nitrogen and in 

 which the other essential dietary components were supplied by 

 adding to the products to be tested a suitable mixture of "pro- 

 tein-free milk," butter fat and starch which, with the addition of 

 adequate protein, has been shown in hundreds of experiments to 

 be sufficient for perfect growth. In this way we have found that 

 satisfactory growth can be made by rats when either cotton-seed 

 globulin or the total cotton-seed protein precipitated from alkali 

 extracts of cotton-seed meal is employed without other significant 

 protein sources in the mixture. No toxic symptoms have ap- 

 peared, even when the supposedly harmful meal also was used, 

 during a period in which the animals reached a large size. In ex- 

 periments in which the inorganic components were furnished by 

 our "artificial protein-free milk" there was no failure of growth 

 when the cotton-seed meal was used, thus suggesting that the 

 latter contains the equivalent of the "determinant," "food ac- 

 cessory," or "vitamin" deemed essential for nutrition and furnish- 

 ed in fat-free milk. These results corroborate the conclusions 

 of Richardson and Green 1 soon to be published. 



83 ("47) 



The early responses of frog embryos to tactile stimulation. 



By Davenport Hooker. 



[From the Anatomical Laboratory of the Yale University School of 

 Medicine, New Haven, Conn.} 



In the course of some experiments on the regeneration of the 

 spinal cord of frog embryos, it became necessary to establish 

 certain facts in regard to their early tactile responses, as has been 

 done for Diemyctylus and Ambly stoma by Coghill. The results 

 of this study are briefly summarized here. 



The frog embryo exhibits a reaction toward the side stimulated 

 as its first response to tactile stimulation with a fine human hair. 

 This occurs so constantly that it must be regarded as normal for 

 the frog, though only an occasional and aberrant reaction in the 



1 Loc. cit. 



