Vlll. KKFKCTS OF DKFK'IKNCV IN ANIMALS 325 



levels of vitamin A, aitlu)ugli there had heen no increase in the intake of 

 \-itanun A. Bassett et a/."-* found that administration of ascorhie acid in- 

 creased the plasma and tissue le\els of vitamin A in foxes and mink and 

 concluded that synthesis of vitamin C is dependent upon the supply of 

 vitamin A. Mitolo^''-'' reported that the a- and /3-carotene contents of tlie 

 livers of scorbutic guinea pigs were somewhat lower than in normal animals. 

 Significance of these results may l)e (questioned l)ecause food intake was 

 not controlled. Stewart^^^ reported that ascorbic acid in daily doses of i.")() 

 mg. produced as great an improvement in dark adaptation of human sub- 

 jects as did daily doses of 24,000 I.U. of vitamin A. The general trend of 

 evidence appears to indicate that the vitamin C status may influence the 

 blood and tissue levels of vitamin A. 



(b) Effect of Mtamin A Level on Content of Ascorbic Acid— Deficiency 

 or Inadequate Supply of Vitamin A. Several investigations have shown 

 a reduction in the ascorbic acid content of the organs of vitamin A-deficient 

 rats, but unfortunately in some of them there was no control of food in- 

 take.^-^^' »37-339 ^ similar effect has been shown in cattle,''^'' but it was not 

 found in mature chickens.-'*' In studies of avitaminosis A in rats, Sjoberg'*^- 

 found that histological changes in the teeth and muscles paralleled the 

 decreasing l)lood ascorbic acid level. He concluded that the organs \vhich 

 sjnithesize ^•itamin C are damaged in vitamin A deficiency. Me\Tr and 

 Krehl'^'*'' observed symptoms resembling scurvy in rats maintained on a 

 vitamin A-deficient diet supplemented with B vitamins in crystalline form. 

 The scurvy-like condition was associated with enlarged adrenals and a 

 diminished ascorbic acid content of the li\'er, adrenals, and blood. The 

 scorbutic symptoms but not the vitamin A-deficiency symptoms were 

 curable with ascorbic acid. Guerrant^''"'" conducted tests with rats using 

 the U.S.P. vitamin A-deficient diet in which the B \'itamins were supplied 

 by brewer's yeast and found that the growth and physical condition of the 

 groups recei\'ing and not recei\'ing ascorbic acid were similar, no scurvy-like 

 symptoms being observed, lie .suggested that the variation in the forni of 



»" C. F. Bassett, J. K. Loosli, aiul F. Wilke, J. Nutrition 35, 629 (1948). 



"5 C. Mitolo, Boll. sac. ital. biol. sper. 17, 310 (1942). 



"• C. P. Stewart, ./. Physiol. 96 Proc. 28 (1939). 



'" B. Sure, K. M. TheLs, ami I{. T. Harrelson, ./. Biol. Chcni. 129, 245 (1939). 



"8 G. Jonsson, A. L. Obel, and K. Sjoberg, Z. Vitaminfor.srh. 12, 300 (1942). 



"» M. Sangiorgi, Boll. soc. ital. biol. s^per. 17, 369 (1942). 



"» P. D. Boyer, P. H. Phillips, W. D. Pounden, C. W. Jensen, I. W. Kupel, and. 



M. E. Nesbit, J. Nutrition 23, 525 (1942). 

 "' M. Rubin and H. R. Bird, Poultry Sci . 22, 53 (1942). 

 '« K. SjohoPK, Kgl. Lantbrukmknd. Tidskr. 80, 445 (1941). 

 '" J. .Mover, and W. .\. Krehl, Arch. Biochcm. 16, 313 (1948). 

 "^ X. B. Guerrant, Science 108, 724 (1948). 



