22 



EVOLUTION AND DISEASE. 



in company with several others, are preserved in the 

 museum of the Royal College of Surgeons (fig. n). 



The additional supply of blood to a part abnormally 

 functional or irritated seems to be largely due to nervous 

 influence, as the following experiments show. Bidder 

 excised a piece of the sympathetic nerve in the neck of 

 a young growing rabbit. This was followed by over- 



FIG. ii. The head of a cock with its spur transferred 

 to the comb. 



growth of the ear of the same side. The experiment 

 has been repeated by Sterling on young and growing 

 rabbits, and on dogs. A piece of the vagus and sym- 

 pathetic for in dogs both nerves are contained in the 

 same sheath was excised. In all cases the ear on this 

 side became distinctly longer, broader, and somewhat 

 thicker than its fellow. The hair was longer and 



