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which excited much discussion. He was also awarded the 

 Copley medal by the Eoyal Society for his original researches in 

 comparative anatomy, and about the same time he engaged an 

 assistant named Cliff specially to work at his museum, which he 

 designed to make illustrative of the whole animal series. To 

 show how his active mind turned all matters to good account it 

 may be mentioned that in 1767 he ruptured the tendon achiliis 

 while dancing ; this is the great tendon of the leg attached to 

 the back of the heel. This accident led him to investigate the 

 mode of repair of injured tendons. In 1783 he purchased a 

 house in Leicester-square, where he removed and built a spacious 

 museum costing £3,000. He was then at his best, full of energy 

 both of body and mind, and in the next five years published 

 many of his most important works. At this time also, assisted 

 by Jenner, the discoverer of vaccination, he investigated the 

 question of colour blindness. In July 1785 he made some ex- 

 periments which led to one of the greatest improvements in 

 surgery, and which more than any other will ever be associated 

 with Hunter's name ; in fact it is now universally spoken of as 

 the Hunterian operation for aneurism. It was the I'esult of a 

 splendid train of inductive reasoning, and illustrated how his 

 mind amid all its investigations and speculation was intent upon 

 practical ends. The experiments in the first instance were under- 

 taken to determine the nature of the growth and casting off of the 

 antlers of the deer. The antlers are confined to the male, and are 

 deciduous, appearing at the end of each spring and falling in the 

 autumn. During their growth, which is marvellously quick — 

 the antlers of a full-grown stag being produced in ten weeks — 

 there is a much greater supply of blood to the head, the vessels 

 carrying it being greatly enlarged. At first the horns are soft, 

 highly sensitive, and covered with a delicate hairy integument, 

 called the velvet, which has many blood vessels. On attaining 

 their full growth a ring of bone forms around the base of each 

 horn and cuts off the blood ; the velvet then shrivels and peels 

 off, leaving the antlers ready to be used as weapons of war. In 

 the autumn they are cast, to be reproduced in the following 

 spring. The experiment Hunter made was to tie on a buck with 

 a half-grown antler one of the carotid arteries. These arteries 

 carry most of the blood going to the head. He found that the 

 immediate effect was that the velvet became cold, and he debated 

 with himself as to what could be the final effects. Would the 

 horn be prematurely cast off, or would its growth only be so 

 retarded that it would be retained much beyond the ordinaiy 

 period "? In a week or two, he had the animal examined again, 

 and was greatly surprised to find that the velvet was quite warm, 

 and that the antler was growing at about its natural rate. The 

 question then suggested itself, had his operation been complete ? 



