38 
M. D. HOGE, JK. 
lation to syphilis; others that it is either a peculiar form of 
malacia or the results of the same. It generally appears in 
children from two to three years of age, among the wealthy 
as well as the poor, and sex has no influence on its occur¬ 
rence. 
Rachitis is a disturbance of the normal process connected 
with the growth of bone. It is not that they become soft, but 
they remain soft, i.e., not ossified. We know that all the 
bony structures of the foetus, except the vault of the cranium, 
are mapped out in hyaline cartilage. Pathologically, we 
find the periosteum much reddened and congested. In tear¬ 
ing off the periosteum small pieces of the unossified tissue 
adhere to it. 
In normal (long) bones, at the epiphyses the proliferative 
layer or hyperplastic zone is sharply and distinctly separated 
from the osseous layer or zone of calcification. In rachitic 
bone the sharp boundaries are replaced by an irregular ser¬ 
rated edge- 
The proliferation of the cartilage cells has increased be¬ 
yond all bounds, and the cartilage matrix has become fibrous. 
There is also an extremely active new growth of blood¬ 
vessels. 
The periosteum shows changes also; the inner or osteo¬ 
blastic layer is thickened and the newly formed bone does not 
become completely calcified, but remains soft and spongy. 
Hence we have swelling of the epiphyses of the long 
bones and thickening of the flat bones, especially those of the 
skull. Normal dry bone contains about 63 per cent, of lime, 
rachitic bones have only 20 per cent, to 30 per cent. 
Experimental proof on animals shows us that when the 
lime salts are withdrawn from the food of ewes, the lambs 
suffer from rachitis. In zoological gardens, young lions and 
leopards also have rachitis when the bones are first cut off 
from the fresh meats fed to them. 
To state the views again as to the causes of rachitis, most 
authors maintain that it is a disturbance of nutrition in which 
the lime salts are deficient. Kassowitz seeks to explain the 
cause by a pathologically increased vascularization of the 
