144 INANITION AND MALNUTRITION 



comparison with the norms of Wilms and Sick, the centers of ossification in rachi- 

 tic children usually appear normal in time, but are delayed in severe cases. 

 Jenner ('95) emphasized the arrested growth of the bones in rickets. Lehnerdt 

 ('10) concluded that in infantile rickets the skeletal mass is usually normal or 

 even increased. Voit ('80) and Dibbelt ('09) found the weight of the fresh 

 bones and cartilages normal or above in puppies with rickets produced by cal- 

 cium-poor diet (extracted meat plus fat). Jackson and Carleton ('23) likewise 

 found nearly normal weights, in proportion to body weight, for both the liga- 

 mentous and cartilaginous skeleton in rats with experimental rickets (Table 11). 

 In nearly all cases, however, there was found a marked, but variable, decrease in 

 the dry weight of the skeleton — a conclusion supported by a large number of 

 observations in the literature on rickets in man and other mammals. Owing 

 to this loss (chiefly of calcium phosphate) the dry content of the bones during 

 rickets may decrease from about 65 per cent down to 30 per cent or less, depend- 

 ing upon the stage and severity of the lesion. 



As previously mentioned, the experiments on diets deficient in calcium and 

 in phosphorus have been made chiefly to determine the cause of rickets. As 

 early as 1839, Guerin noted that the bones in puppies on a meat diet become 

 softened and deformed, and he made the diagnosis of rickets produced by lack of 

 calcium phosphate. Roloff ('66, '75) confirmed these results, finding softening 

 of the long bones, scapulae, pelvic bones, vertebrae, etc. The epiphyseal joints 

 become enlarged, forming a " rickety rosary" along the costochondral junctions. 

 The bones become lighter (due to osteoporosis) and the thorax elongated dorso- 

 ventrally. The condition develops most readily in young, rapidly growing 

 puppies. Although no histological examination was made, it was diagnosed as 

 rickets, due to lack of calcium. The addition of calcium salts to the diet pre- 

 vented the disease, but non-calcium salts (including phosphates) did not. 

 Friedleben ('60) recognized clearly that the osteoporosis produced in pigeons 

 by mineral-poor diets differs fundamentally from true rickets. 



The first production of experimental rickets in which the histological struc- 

 ture was carefully studied was apparently that of Wegner ('72). He found that 

 the addition of small doses of phosphorus to the ordinary diet stimulates osteo- 

 genesis in young animals (calf, rabbit, chicken). A salt-extracted grain diet in 

 young chickens makes the bones soft, thin and brittle (confirming Chossat '42). 

 The addition of phosphorus to this diet was found to produce rickets. 



"Aeussert interessant ist es, dass unter dem gleichzeitigen Einfluss der 

 Phosphorfiitterung und der Entziehung anorganischer Substanzen, namentlich 

 des Kalkes, der Wachstumsmodus der Knochen eine Aenderung erfahrt, die 

 auf das vollkommenste dem entspricht, was wir beim Menschen als Rachitis 

 zu bezeichnen gewohnt sind (Taf. 1, Fig. 34). Man sieht bei einem Ver- 

 gleich mit dem daneben stehenden normalen Knochen an dem Beispiel 

 gewahlten oberen Ende der Tibia eines jungen Huhnes die ausserordentliche 

 hohe, von zahlreichen weiten Markraumen durchzogene gallertig, durch- 

 scheinende gewucherte Knorpelmasse; in sie greift sehr unregelmassig in wellig- 

 hiigeligen Linien ein die Zone der Kalkinfiltration, die tibrigens an sich sehr 

 unvollkommen ist. An der Stelle, wo sich ausgebildete, weitmaschige spongiose 



