THE FOLIC ACID COMPLEX 



maturation arrest of the bone marrow, suggesting that pteroylglutamic 

 acid may not be necessary for the formation of the immature blood 

 elements but is necessary for maturation after the primitive elements 

 have been formed.^^" 



Guinea-pigs 



D. W. Woolley and H. Sprince *^ identified folic acid as one of the 

 growth factors required by the guinea-pig ; this had previously been 

 designated GPF-i. 



Dogs 



W. A. Krehl and C. A. Elvehjem ^^ found that young dogs main- 

 tained on a nicotinic acid-deficient diet until severe symptoms of black- 

 tongue developed responded poorly to supplements of nicotinic acid 

 and soon died despite the administration of what would normally have 

 been adequate amounts of nicotinic acid. When the basal diet was 

 supplemented with a folic acid concentrate (from " solubilised liver ") 

 the response to nicotinic acid was consistently good. 



Foxes 



On a diet free from the vitamin B complex, but containing aneurine, 

 riboflavine, pyridoxine, nicotinic acid, pantothenic acid and choline, 

 foxes developed anaemia and anorexia, lost weight and eventually 

 died.^^ Administration of folic acid resulted in immediate recovery 

 with rapid regeneration of haemoglobin and red blood cells. Yeast 

 folic acid conjugate was not utilised by foxes, but the substance was 

 effective after hydrolysis with kidney enzyme. Folic acid was not 

 the only factor required, however. 



Mink 



Absence of folic acid from the diet caused deficiency symptoms in 

 the mink, characterised by irritability, weakness, bloody faecal dis- 

 charge, anorexia, loss of weight, fall in the white cell count and, 

 eventually, death. ^^ Folic acid cured most of these symptoms 

 promptly, but another factor appeared to be necessary for maintenance 

 of weight and for haemoglobin regeneration. 



Pigs 



Folic acid alone or in combination with ^-aminobenzoic acid, 

 inositol or biotin appeared to have no beneficial effect on the growth 

 or appearance of pigs, although haemoglobin formation was stimulated 

 to a small extent. ^^ On the contrary, symptoms of biotin deficiency 



490 



