

EFFECTS ON THE SKELETON 141 



relation of minerals to the growth and structure of the body, and especially 

 of the skeleton. "The readiness with which minerals may be deposited in the 

 bones, the lack of a definite upper limit of such a deposit, and the readiness 

 with which these minerals may be withdrawn constitute the skeleton a true 

 store of mineral nutriment." McClendon ('22b) states that in a normal white 

 rat weighing about 70 g. the skeleton contains 82 per cent of the phosphorus 

 and 96 per cent of the calcium in the body. 



In most of the earlier experiments, the mineral deficiencies were complicated 

 by other (especially vitamin) deficiencies, so their interpretation is often 

 uncertain. 



Calcium Deficiency. — It is difficult to consider the effects of calcium 

 deficiency aside from the question of rickets. Some of the more general effects 

 of calcium deficiency upon the skeleton will be mentioned now, leaving those 

 papers dealing more specifically with rickets for later consideration. 



Chossat ('42) observed that on diet of wheat (calcium-poor) and water, 

 adult pigeons die before 10 months with a diarrhea and skeletal lesions ascribed 

 to the calcium deficiency and prevented by addition of calcium carbonate to 

 the diet. The bones, especially the femur and sternum, become very porous, 

 softened and fragile, so as to fracture easily. Similar results were obtained 

 by Friedleben ('60), Milne-Edwards ('6i) (with loss of ^ in weight of the 

 skeleton), C. Voit ('81) and numerous more recent workers. E. Voit ('77) 

 found that in pigeons on calcium-poor diet the bones more actively used in 

 movements and support retain their calcium content longer, while the inactive 

 (e.g., skull and sternum) become porous and thin. The negative results of 

 Weiske ('71, '74) and Weiske and Wildt ('73) with goats, rabbits and lambs 

 on calcium-poor diets were ascribed by later investigators to starvation (total 

 inanition) since the animals refused the food. Numerous more recent workers 

 have investigated the histological changes in the skeleton of various animals 

 on different calcium-poor diets, and have described, in addition to the resorp- 

 tive changes associated with osteoporosis, variable other lesions more or less 

 closely related to those of rickets (to be mentioned later). 



According to Kellner ('16) fragility of the bones occurs also in the large 

 domestic animals on calcium-poor diets. The relation between malnutritional 

 and senile osteoporosis has been emphasized by Alwens ('19) and others. 

 Rubner ('20a), however, states that the bone lesions occurring during the war 

 famine were not curable by calcium alone. McClendon ('22a) found that low 

 calcium diet produced osteoporosis in young rats, with marked reduction in 

 the thickness of the wall in the shafts of the long bones. 



Dibbelt ('n) cites evidence indicating that there is a "physiological osteo- 

 porosis" in the skeleton of the human infant and in the young of other animals. 

 He ascribed this to the relative poverty of calcium in the milk, a condition which 

 favors bone resorption. Wieland ('13) also reviewed the evidence for "physi- 

 ological osteoporosis," but found no proof of a universal calcium-deficit in the 

 nursling's milk. In the case of the human infant, it is difficult to exclude the 

 possibility of latent rickets, scurvy or similar disorders due to dietary 

 deficiencies. 



