322 THE VITAMINS 



work with dogs. They believe "that while a reduction of inorganic 

 phosphate need not necessarily precede the incidence of severe rickets, 

 sooner or later in the course of the disease, such a reduction results. 

 When this reduction has taken place, with amelioration of the symptoms 

 and cure of the disease, the composition of the blood is restored to 

 normal." . . . "Just what the normal is for the dog is difficult to say, 

 apparently it varies." . . . "It is certain that comparisons can only be 

 made on the same animal." 



Cavins (1924) reported that the normal inorganic phosphorus con- 

 tent of the blood serum of rats is "7 to 8.5 mg. per 100 cc. In animals 

 rendered rachitic by a diet low in phosphorus (such as diet No. 3143 of 

 McCollum) the phosphorus is found to be about 3 mg. per 100 cc. and 

 may run as low as 2 mg." 



Dutcher, Creighton and Rothrock (1925) found the inorganic phos- 

 phorus of the blood serum to be 10 milligrams per 100 cubic centimeters 

 in 3-week-old normal rats, and 8 milligrams per 100 cubic centimeters in 

 11 -week-old rats on a normal diet. Rats put on a rachitic diet (No. 2965 

 Steenbock) at 3 weeks of age, had by the time they were 6 weeks old 

 (21 days on the experimental diet) 1.6 milligrams inorganic phosphorus 

 per 100 cubic centimeters blood serum. 



Hess, Weinstock, Rivkin and Gross (1930) found that when in- 

 adequate amounts of antirachitic agents were given, such as poorly 

 irradiated milk or irradiated ergosterol, and mild rickets resulted, con- 

 centrations of 6 milligrams or more of inorganic phosphorus and of 10 

 milligrams or more of calcium per 100 cubic centimeters of blood serum 

 were found. In the case of inadequate cod-liver oil, positive line tests 

 were secured, but the blood phosphorus remained low. When extreme 

 rickets was induced by feeding a diet with a very high ratio of calcium 

 to phosphorus and large amounts of cod-liver oil and irradiated 

 ergosterol were fed, the rachitic lesions in the epiphyses were unaffected 

 or gave evidence of slight healing after a 9-day test period, whereas the 

 blood had a normal or an excessive concentration of calcium and phos- 

 phorus. These authors state that, "the established fact that the inorganic 

 phosphorus of the blood is generally diminished in rickets has led to the 

 inference that the disturbance associated with this disorder is of a 

 systemic nature and that local factors play no part in its pathogenesis. 

 ... It seems to us that these observations, considered in conjunction 

 with our experiments, indicate that there is probably a local as well as 

 a systemic factor which prevents the calcification of the epiphyses in 

 rickets — something which is lacking in order to bring about a binding 

 of the calcium and phosphorus." 



