Nutrition 129 



larvae and for pupation and pigmentation.'*^ Young turkeys on a diet defi- 

 cient in folic acid show retarded growth and anemia, whereas in mice hemato- 

 poiesis in the bone marrow is arrested, with a hyperplasia of immature cell 

 types.^^-' Folic acid is essential for mink,^^*^ and in monkeys a folic acid 

 deficiency results in lack of growth, anemia, and reversed lymphocyte/neutro- 

 phile ratio.-** Further investigation will probably indicate a wide need for 

 folic acid, particularly in growth and cell division. 

 Folic acid has the following structure: 



H H /\ /X 



C-C^ HC C C-NH. 



/ X I II I 



HOOC-CH.-CH,-CH-NH-C-C NH-CH^-C C N 



I II \ / \ / \ / 



COOH O C^C N C^ 



H H OH 



Vitamin Bi,- The anemias which develop in animals deficient in riboflavin, 

 pyridoxine, pantothenic acid, or niacin are microcytic, that is, characterized by 

 the presence of undersized red cells in the blood. Macrocytic anemia, with 

 small numbers of large red cells, occurs in deficiency of folic acid and of 

 vitamin Bio. Vitamin Bio has been crystallized and shown to contain co- 

 balt, ^^^ but its chemical identity is not yet known; it is derived from liver and 

 is effective against macrocytic anemia, even with central nervous system in- 

 volvement. It is a specific anti-pernicious anemia factor. Vitamin Bio not only 

 stimulates hematopoiesis but also promotes growth in chickens, rats, and pigs, 

 and it may be identical with some of the unknown factors found for various 

 animals. There is evidence for interaction between Bio and pteroylglutamic 

 acid, and in certain human macrocytic anemias pteroylglutamic acid is effective 

 when vitamin Bio is ineffective. In some bacteria, vitamin Bi_. is concerned 

 with the ability to synthesize nucleosides, particularly thymidine. '-'' Vita- 

 min Bio is required by Euglena gracilis for maximum growth ''■' and also by 

 Astasia klehsii (Thayer and Kidder, unpublished), whereas it is synthesized 

 by Tetrahyniena. 



Miscellaneous B Vitamins. Choline and inositol are two substances which 

 are widely distributed in animal tissues and are probably synthesized by most 

 animals, but the rate of synthesis may not be adequate for the cellular needs; 

 hence they are sometimes considered as vitamins. Choline is a constituent of 

 lecithin and other lipids and is a precursor of acetylcholine, a substance im- 

 portant 'in nerve function (Ch. 23). Choline serves, in addition, as a source 

 of labile methyl groups needed in transmethylation processes; it is synthesized 

 from methionine and ethanolamine in the rate; methionine also can function 

 as a methyl donator. If a diet is low in protein, particular!)' in methionine, and 

 high in fat, choline is then a dietary essential, and in such choline deficiency 

 rats show hemorrhages, increase in liver fat, and ultimately renal degeneration. 

 Choline is essential in fatty acid metabolism. It has a favorable action on 

 growth in numerous insects. It is the most essential vitamin for the cock- 

 roach, '°^ but apparently many other insects synthesize it in adequate amounts 

 (Table 24''0- Unlike the rat, the cockroach evidently does not make choline 

 from ethanolamine and methionine; however, betaine (trimethyl glycine) can 



