PRINCIPLES OF VETERINARY SURGERY 591 



consist of defective development and defective classification. 

 The rickety bone is but slightly resistant. It is easily bent, 

 deformed, fractured or severed. The deformities are varied. 

 The long bones exhibit incurvations of the diaphyses and 

 rickets of the epiphyses. They are swollen at the cartilage 

 of conjugation. On section they appear very red and very 

 vascular. The cartilage of conjugation is large, thick, hy- 

 pertrophied, bluish or violet colored, and in its surrounding 

 tissues are seen small cartilaginous nodules, scattered pro- 

 miscuously and enclosed in osseous tissue. From the carti- 

 lage irregular spaces project into the diaphysis. All these 

 structures are very vascular, non-resistant and areolar, and 

 if scraped they are found to be encrusted w^ith calcareous 

 salts. Under the periosteum the tissue is reddish and areo- 

 lar, very non-resistant, pits on pressure with the fingers, 

 and cuts easily with a knife. The periosteum is thickened 

 and very vascular. When removed it leaves the surface 

 of the bone knotty and porous. The medullary canal is 

 larger than normal and the marrow is rich in blood-vessels. 

 In the flat and long bones there is marked vascularity and 

 rarefaction of the cancellated tissue. All of the bones are 

 affected, but in unequal proportions. Everywhere the inor- 

 ganic substance has diminished, especially in its phosphate 

 of lime. The organic substance and the adipose tissue are 

 augmented. 



The lesions have been but little studied, microscopically, 

 in animals. In man Carjiil distinguishes three periods: (i) 

 period of commencenient ; (2) period of deformity; and (3) 

 period of repair. The first period is characterized by altera- 

 tions of the epiphyseal cartilages. They are thickened and 

 the zone of ossification exhibits an increase in all its di- 

 ameters. Instead of possessing its normal thickness of one 

 millimeter it may reach a centimeter or more, and its edges 

 are crumpled and irregular. The cartilaginous projections 



