1920.] 



Accessory Food Factors. 



667 



stuffs; this factor is probably identical with that, the absence 

 of which leads to rickets in young. This factor is in all 

 probability synthesized by the plant, and its primary sources 

 are found in the green leaves of plants and the embryos of 

 certain seeds. Beyond these primary sources the main sources 

 are certain fats of animal origin, such as butter. The distribu- 

 tion of this factor in foods will be found in the Table concluding 

 this account. 



This factor is gradually destroyed at 100° C. (the boiling 

 point of water) , and four hours' exposure to that temperature 

 is sufficient to render butter-fat of little greater nutritive value 

 from the standpoint of vitamine supply than an equivalent 

 quantity of lard. The factor is also destroyed during 

 the hardening of oil by the action of hydrogen, a process now 

 widely employed for the preparation of edible fats such as 

 margarine. 



We as yet know nothing definite of the part this factor plays 

 in the nutrition of the body. Storage of the factor appears to 

 be particularly marked in adult animals, and the requirements 

 after maturity is reached are of a smaller order than those of 

 "the growing young. Such storage is of considerable import- 

 ance to the pregnant and nursing mother, for she can provide 

 her young with a high concentration of this factor without 

 immediate dependence upon an external supply. 



(2) Water Soluble B Factor. — This term is also that of 

 American investigators, this factor being soluble in water; and 

 it is probably identical with the anti beri-beri and anti-neuritic 

 factor. The primary sources of this factor also are provided by 

 the plant kingdom. It is widely distributed, having been 

 found in all the natural foodstuffs examined, and it apparently 

 exists free in the plant cell. The principal sources have proved 

 to be the seeds of plants and eggs of birds. In cereals the 

 largest deposit is found in the embryo or germ, the bran 

 coming next, while the endosperm is deficient. This fact 

 accounts for outbreaks of the disease beri-beri among peoples 

 existing on a diet of polished rice. 



The requirements of the body for this factor are much greater 

 during growth than maturity, and the large deposits in seeds 

 and eggs suggest a due provision made for the wants of the 

 young offspring during the early period of life. It does not 

 seem that the normal animal possesses any large reserve of 

 the water-soluble factor in an available form, and while (as in 

 the case of the fat soluble factor) the quality of the milk of the 



