THE VITAMINES IN THE ANIMAL KINGDOM 143 



(417) observed that between wheat and corn, there are great differ- 

 ences as regards the growth-promoting properties. While the 

 animals attained a weight of 100 pounds on wheat, on corn they 

 weighed from 200 to 300 pounds. McCollum (418) fed young pigs 

 on wheat, oats and corn and found that casein, as well as skimmed 

 milk, was a better source of nitrogen. After three months, the 

 animals declined and McCollum left the question open as to whether 

 this condition was due to lack of salts or vitamine, or to the presence 

 of a toxic substance. Hart and McCollum (419) could not keep 

 young pigs alive for a long time on corn and gluten, while the addition 

 of casein or milk appreciably improved growth. Hart and Steenbock 

 (420) investigated a series of plant products, with the addition of 

 the same animal foods as above, and came to the conclusion that 

 rice, wheat, corn, potatoes, and cabbage possessed little nutritive 

 value, but it was not further investigated whether the vitamines 

 played a role. Later, Hart and Steenbock (421) sought to settle 

 the question as to whether the presence or absence of vitamines has 

 any effect. For this purpose, grown pigs were kept for a long time 

 on corn and oats. Eventually, symptoms of the disease appeared, 

 such as stiffness of the legs and difficulty of getting about, these 

 conditions being specially manifested in pregnancy and lactation. 

 A great number of young were born dead. If these symptoms were 

 not noticed in the first litter, they were present in the second. In 

 most cases, an improvement was seen when the cereal diet was sub- 

 stituted by a corn-alfalfa mixture, which is much richer in vitamines. 

 The dietary deficiency was however attributed largely to the unfavor- 

 able composition of the inorganic constituents. These exact experi- 

 ments are particularly important for the recognition of the etiology 

 of some very frequently occurring diseases of cattle which are of 

 practical importance, and which have lately been quite often attrib- 

 uted to the effect of a poison. We see, however, that feeding in 

 the stable may lead to dietary deficiencies, without it being necessary 

 to assume a toxic cause. 



The superiority of skimmed milk over all other food mixtures was 

 also set forth in a number of publications of Klein (422). This 

 favorable influence may be explained either by a better utilization of 

 the protein, by the vitamine content, or by both factors. 



Despite all these investigations, and still others to be mentioned, 

 we are not yet accurately informed as to the vitamine requirements of 



