RICKETS 323 



investigators, among whom should be mentioned Phemister (I.e. 

 1112), Rowland and Park (1116), and Dufour (1116a) and Hess. 

 The results of cod liver oil therapy are apparent in animals some- 

 times after only two days; in children, after about three weeks, when 

 the deposition of calcium may actually be noted. This method is 

 coming into general use, and will very likely become of great prac- 

 tical importance. 



ETIOLOGY 



Although we accept the vitamine etiology in rickets, we are well 

 aware that still other views for the explanation of the nature of this 

 disease have been advanced. One of these hypotheses, the causal 

 relationship with the endocrine glands, we have already discussed in 

 detail in our first edition, and will, therefore, not go into it again here. 

 Since the function of the vitamines, especially vitamine A, is entirely 

 unknown, the vitamins hypothesis in rickets does not exclude the 

 possible role of the glands in the development of rickets. The 

 study of the etiology of rickets has been in a state of change during 

 the past year. According to the results of modern experimental 

 rickets investigations, this disease seems to' be associated with a 

 number of factors a fact which might assign to rickets a special 

 place in pathology. Three such factors have been put in the fore- 

 ground lack of vitamine A, lack of phosphorus and lack of sun- 

 light. Each of these factors alone is able to cure the disease, which 

 develops as well in rats and dogs as in man, and has a favorable 

 influence on the calcium metabolism. Similar results have already 

 been obtained with children. Nevertheless, it is not yet clear as to 

 just how these three factors are related to each other. They give, 

 at all events, the same pathological picture. The "domestication, 

 theory" of v. Hansemann (1117) and also of Kassowitz (1118) has 

 recently been accentuated by a number of English investigators 

 Findlay (1119), Paton, Findlay and Watson (1120) and Ferguson 

 (I.e. 1115), and by the modern sunlight hypothesis. Dick (1122) 

 believes that rickets is a disease of great industrial centers, and that 

 it does not occur in the tropics, Japan or China. However, this 

 seems to have little foundation in fact. Although we do not wish 

 to state, at this time, that a poor hygienic condition has nothing 

 whatever to do with the etiology of rickets, we believe, nevertheless, 

 that it can not be the only cause. For, as it most frequently hap- 



