558 DISEASES OF THE ORGANS OF LOCOMOTION. 



urine, the material for the formation of bone-substance is withdrawn 

 from the blood. But this hypothesis is not tenable ; the increase of 

 lactic acid and phosphate of lime in the urine of rachitic children is 

 not constant. Rachitis not unfrequently develops without precedent 

 disturbance of the digestion or formation of acid, and the proliferation 

 of the epiphyseal cartilages and of the periosteum, which are just as im- 

 portant factors of rachitis as the retarded deposit of calcareous salts is, 

 cannot be explained by the excretion of phosphate of lime through the 

 urine. Virchow, to whom we owe the most important explanations 

 of the histology of rachitic bones, and the pathogeny of rachitis, 

 says that the cause of the retarded ossification is more probably a 

 diminished supply of chalky salts than their increased excretion 

 through the urine. He reminds us of the recommendations of the car- 

 bonates and phosphates of lime as remedies in rachitis, and calls par- 

 ticular attention to the fact that, in the dyspepsia of children, which 

 usually precedes rachitis, as there is less albuminate taken into the 

 system, the amount of earthy salts required for the normal growth of 

 the bone absorbed is also diminished, as they are, for the most part, 

 introduced into the body as albuminate. Virchow does not pretend 

 that this view also is not problematical. It does not explain why the 

 disturbance of the supply of nutritive material should affect the bones 

 more than the other parts ; it is also opposed by the fact that rachitis 

 occurs not only in dyspeptic children, but also in those who are other- 

 wise well nourished ; lastly, it is evident that the diminished supply 

 of nutritive material does not suffice to explain also the proliferation of 

 the epiphyseal cartilages and of the periosteum. From these considera- 

 tions, it seems to me that the most probable hypothesis regarding the 

 cause of rachitis is that which refers it to inflammation of the epi- 

 physeal cartilages and periosteum. In other tissues, also, as in the skin, 

 mucous membrane, etc., we often see diffuse inflammations (exanthe- 

 mata, catarrhs, etc.), whose immediate cause we cannot discover. Like 

 rachitis, these occur chiefly, but not exclusively, in badly-nourished, 

 cachectic persons, and are also often accompanied by rachitis. From 

 what we know of periostitis, it is not surprising, as Virchow aptly 

 says, that the disturbance of circulation at the height of the disease 

 should hinder the deposit of calcareous salts in the morbidly-proliferating 

 tissue. Lastly, the excessive excretion of phosphate of lime through 

 the urine may just as well be the result as the cause of the lime-salts 

 not being deposited in the bones. Rachitis is a disease of childhood, 

 and it is doubtful whether the rare cases, where the disease is said to 

 have occurred in adults, or during foetal life, were actually rachitis. 

 The disease is most frequently seen from the second half of the first 

 year till the time of the second dentition ; before the seventh month, 



