352 CARNEGIE INSTITUTION OF WASHINGTON. 



NUTRITION. 



Osborne, T. B., and L. B. Mendel, New Haven, Connecticut. Continuation 

 and extension of work on vegetable proteins. (For previous reports see Year 

 Books Nos. 3-17.) 



During the past year our investigations have followed chiefly the 

 direction indicated in the report for 1918. The extensive study of the 

 nutritive value of the wheat kernel there referred to was continued and 

 a detailed account of the results has been published. In connection 

 with this work we were surprised to find that, contrary to the pre- 

 vailing belief, the water-soluble vitamine of the wheat kernel is not 

 concentrated in the embryo. Although the so-called commercial 

 wheat embryo is much richer in water-soluble vitamine than either the 

 endosperm or the entire kernel, nevertheless, when the pure embryos 

 proper w^ere dissected out from the kernels and fed as the sole source 

 of this vitamine with an otherwise adequate ration, even relatively 

 large quantities of them failed to promote any growth on the part of 

 the rats receiving them. Moreover, the kernels from which the 

 embryos had been removed showed no appreciable diminution in their 

 vitamine activity as compared with the undissected kernels. It thus 

 appears that the water-soluble vitamine is located in the endosperm. 

 That it is not uniformly distributed throughout this part of the kernel 

 is shown by the fact that if about one-quarter of the embryo-free grain 

 is cut off at the embryo end of the seed, that portion near the embryo 

 is more efficient as a source of water-soluble vitamine than is the 

 remainder of the seed, although the latter is by no means devoid of 

 potency. The high vitamine activity of the commercial embryo meal 

 may be caused by a considerable proportion of the softer parts of the 

 endosperm adjacent to the embryo, which in the milling process is 

 removed together with that part of the seed. Our experiments appear 

 to make it certain that if the vitamine is a single substance needed for 

 adequate nutrition, it must be a constituent of the endosperm. The 

 fact that those rats receiving the pure embryo as the sole source of 

 water-soluble vitamine were well maintained for many weeks without 

 growing, whereas those rats receiving the embryo-free grain grew 

 normally, raises the question as to whether the water-soluble vitamine 

 is a single substance or a mixture of two or more. 



A previous report has referred to the desirability of securing some 

 rehable information regarding the comparative nutritive values of the 

 total proteins of different cereal grains which play a prominent part in 

 both human and animal feeding. It was hoped to accomplish the com- 

 parison of the cereal proteins aside from other compHcating factors by 

 removing the greater part of the starch from the rest of the seeds. The 

 experiments w4th protein products concentrated in this way have not 

 proved so satisfactory as was anticipated. Hence we have developed 



I 



