160 Society for Experimental Biology and Medicine. 



lecithin gained, in some cases, as much as 7 per cent, over the 

 control animals. 



Scries j. Lecithin was fed daily in amounts of from 0.0 1 to 

 0.32 gram. With very few exceptions, these kittens weighed 

 from 2 per cent, to 12 per cent, more than the controls. 



The best results were obtained in the feeding experiments, with 

 doses of from 0.04 to o. 16 gram daily ; yet under these conditions 

 the actual difference in weight between the kittens fed with lecithin 

 and those not so fed was small, amounting on an average to about 

 7 per cent. Whether the same quantity of any other fatty or 

 simple nutrient compound would result in an equal increment has 

 not yet been determined, but will be investigated with other mat- 

 ters bearing upon the interpretation of the results recorded above. 



112 (255) 



Comparative data for the elementary composition and the 

 heat of combustion of collagen and gelatin. 



By Charlotte r. manning and William j. gies. 



[From the Chemical Laboratory of Wesley an University, Middle- 

 town, Coiin., and from the Laboratory of Biological Chem- 

 istry, of Columbia University, at the College of 

 Physicians and Surgeons.'] 



Comparative elementary analyses, as well as determinations of 

 the heat of combustion, of many samples of connective tissue col- 

 lagen and gelatin, have indicated that there is a closer agreement 

 between the mother substance and its derivative, on these two 

 planes of comparison, than the prevalent idea of their chemical 

 relationship would indicate. The following sample data show 

 this quite clearly : 



C H N Heat of combustion 



Per cent. Per cent. Per cent. calories. 



Tendocollagen 1 48.85 8.01 18.02 5,387 



Tendogelatin 48.28 7.84 17.56 5>35° 



These data were obtained before the experiments by Emmett 



1 Each of these products was desiccated (before analysis) to constant weight by 

 the Benedict- Manning process in vacuo. See the American Journal of rhysiology, 

 1905, xiii, p. 309. 



