EFFECT OF DEFICIENCY IN ANIMALS 



Fresh calf liver contained o-2 ; ^ and ox liver, 2-5 jug. per g.^ 

 Dried whole egg contained 0-2 to 0-36 ; dried egg yolk, o-8 ; and 



dried egg albumen, 0-055 i^g- P^i" g-^ Skim milk contained 0-004 * 



and whole milk, 0-15 /xg. per ml.^ 



As might be expected, yeast was the richest source of p-amino- 



benzoic acid, containing from 4 ^ to 100 ^ /xg. per g. Mushrooms 



contained 1-3 fig. per g.^ 



References to Section 4 



1. M. Landy and D. M. Dicken, /. Biol. Chem., 1942, 146, 109. 



2. H. K. Mitchell, E. R. Isbell and R. C. Thompson, ibid., 1943. 147, 



485. 



3. R. C. Thompson, E. R. Isbell and H. K. Mitchell, ibid., 1943. 148, 



281. 



4. J. C. Lewis, ibid., 1942, 146, 441. 



5. EFFECT OF p-AJMINOBENZOIC ACID DEFICIENCY IN 



ANIMALS 



The recognition of ^-aminobenzoic acid as a growth factor for micro- 

 organisms (page 546) was soon followed by evidence of its biological 

 importance for higher animals and man. S. Ansbacher^ was the 

 first to suggest that it might be a member of the vitamin B complex, 

 following the discovery that it ciured grey hair in rats, and also in 

 mice,2 when these were fed a synthetic diet. G. A. Emerson,^ however, 

 failed to confirm these observations, but they were substantiated by 

 the subsequent work of G. J. Martin and S. Ansbacher,^ who showed 

 that _^-aminobenzoic acid also counteracted the action of hydro- 

 quinone, which causes greying of hair in cats ^ and mice, and of sul- 

 phanilamide ® and succinyl sulphathiazole,'^ which have a similar 

 effect in rats. Moreover, the colour change normally produced by 

 the action of tyrosinase on dihydroxyphenylalanine was modified 

 by ;/)-aminobenzoic acid in vitro, suggesting that it interfered with 

 melanin formation.^ The interference was not specific, however, since 

 sulphanilamide and alanine, though not pantothenic acid (which has 

 also been claimed to possess chrombtrichial properties) behaved simi- 

 larly. 



According to B. Sure,^ _/)-aminobenzoic acid was essential for re- 

 production and lactation in the rat. 



Since the deficiency symptoms resulting from feeding a purified 

 diet to rats were aggravated by succinylsulphathiazole and at least 

 partially removed by ^-aminobenzoic acid, Briggs et al.^^ suggested 

 that the factor required to prevent these symptoms might be 



