THE B VITAMIN REQUIREMENTS OF ANIMALS AND PLANTS 329 



trend in even these intermediate species follows closely trends in their 

 morphological classification. If one were compelled to state a single dis- 

 tinctive difference between the two kingdoms, it would be difficult to find 

 a better one than that of the ability to synthesize the B vitamins. 



Table 26. Some Reported Requirements of Miscellaneous Mammals for B Vitamins 



Why this nutritional dichotomy developed in the evolutionary process 

 is a matter for considerable speculation. It is apparent that both plants 

 and animals may survive upon the earth in a biological balance when 

 only the one group has the higher synthetic ability, and a philosophy 

 might readily be worked out in terms of a conserving economy in the 

 distribution of metabolic abilities. More practically, since on a global 

 scale the plant and animal kingdoms are interdependent, this difference 



