DISEASES OF THE BLOOD. 



67 



matter. They found that " young animals, with imper- 

 fectly formed skeletons, suffer more from deprivation of 

 lime than adults and directly in proportion to their size. 

 Young dogs fed exclusively on fat and flesh became exten- 

 sively rachitic without any other modification of the general 

 nutrition. The disease consisted in an inflammation of the 

 parts of the bones in which growth occurs, and especially 

 in the most freely moveable rays of the limbs. A similar 

 process occurs, even though the aliment contains sufficient 

 lime, when, from any cause, such as disturbance of diges- 

 tion or use of too great quantities of principles tending to 



Fig. 23. — Rachitic dog (Hill). 



increase the amount of excrement, a small proportion 

 only of the lime in the food is absorbed." These facts 

 agree closely with the conclusions of practical observers 

 that the disease depends on improper food, indifferent 

 ventilation, and the want of exercise, which is so essential 

 to the efficient action of the bowels and development of the 

 frame. It has been observed, also, that it prevails as a 

 hereditary disorder, especially among pugs and small bull- 

 dogs (Blaine), and the breed of wry-legged terriers is 

 supposed to have had its origin in the effects of this 

 disease. Hill very justly warns us against concluding 



