VI. EFFECTS OF DEFICIENCY 225 



also common if the disease is in an advanced state. In the rat, enlargement 

 of the carpal joint appears to be rather characteristic. 



2. Growth 



As mentioned above, Bechtel et at} found decreased growth in ricketic 

 calves, and Steenbock and Black^** used the increase in weight of rats over 

 the ricketic controls as a criterion for the activity of antiricketic substances. 

 Hart et al}^ have demonstrated the marked effect of sunlight on the growth 

 of chicks on a synthetic diet which contained ample calcium and phosphorus 

 but was low in vitamin D. The ^dtamin A was supplied by fresh ground 

 clover. One group was given the basal ration without sunlight, and the 

 other received the same diet but was exposed to summer sunlight one-half 

 hour each day. At the end of 6 weeks on the experimental diets the two 

 remaining ricketic fowls weighed 80 and 90 g., respectively, and the two 

 controls weighed 145 and 180 g. The authors present radiographs of one 

 bird from each diet which show a pronounced difference in the degree of 

 calcification, especially of the long bones. Evidence that the lack of vitamin 

 D also markedly inhibits the growth of pups has been presented by Steen- 

 bock et al.-'^ Steenbock has repeatedly emphasized the essential requirement 

 of vitamin D for growth. 



The relation of rickets to growth has also been discussed by Rosenberg.^i 

 He believes that this effect is of primary significance and not secondary 

 to other factors such as anorexia. 



3. Calcium and Phosphorus of the Serum 



One of the most consistent changes in the composition of the blood during 

 rickets is a decrease in the level of inorganic phosphate, which was first 

 noted by Howland and Kramer^^ while working with children. In Table X are 

 given the calcium and inorganic phosphorus in the serum of two ricketic 

 litter-mate pups as well as the calcium and phosphorus in the serum of three 

 other members of the same litter which were on the identical basal diet 

 but received vitamin D in addition.-" The level of these blood constituents is 

 given at 6 and 9 weeks after the pups were put on the experimental diet. 

 Both the calcium and inorganic phosphorus are considerably lower in the 

 serum of the ricketic than control animals. The calcium, although low, is 

 about the same at 6 weeks and 9 weeks on the diet, but the phosphorus is 

 considerably lower at the later period than it was earlier. Bechtel et al^ 



'« H. Steenbock and A. Black, ./. Biol. Chem. 61, 405 (1924). 



" E. B. Hart, H. Steenbock, S. Lepkovsk}^ and J. G. Ilalpin, J. Biol. Chem. 58, 33 

 (1923-1924). 



" H. Steenbock, J. H. Jones, and E. B. Hart, /. Biol. Chem. 58, 383 (1923-1924). 



2' H. R. Rosenberg, Chemistry and Phj^siology of the Vitamins. Interscience Pub- 

 lishers, New York, 1942. 



22 J. Howland and B. Kramer, Am. J. Diseases Children 22, 105 (1921). 



