16 



THE BLOOD 



in Richmond Park, to see the influence of ligature 

 of the carotid artery on the growth of the antler. 

 The following account of this experiment was 

 given by Sir Richard Owen, who had it from 

 Mr Clift, Hunter's devoted pupil and friend : — 



" In the month of July, when the bucks' antlers 

 were half-grown, he caused one of them to be caught 

 and thrown ; and, knowing the arterial supply to the 

 hot 'velvet,' as the keepers call it, Hunter cut down 

 upon and tied the external carotid ; upon which, lay- 

 ing his hand upon the antler, he found that the 

 pulsations of the arterial channels stopped, and the 

 surface soon grew cold. The buck was released, 

 and Hunter speculated on the result — whether the 

 antler, arrested at mid-growth, would be shed like 

 the full-grown one, or be longer retained. A week 

 or so afterward he drove down again to the park, 

 and caused the buck to be caught and thrown. 

 The wound was healed about the ligature ; but on 

 laying his hand on the antler, he found to his sur- 

 prise that the warmth had returned, and the channels 

 of supply to the velvety formative covering were 

 again pulsating. His first impression was that his 

 operation had been defective. To test this, he had 

 the buck killed and sent to Leicester Square. The 

 arterial system was injected. Hunter found that the 

 external carotid had been duly tied. But certain 

 small branches, coming off on the proximal or heart's 

 side of the ligature, had enlarged ; and, tracing-on 

 these, he found that they had anastomosed with 

 other small branches from the distal continuation of 

 the carotid, and these new channels had restored 

 the supply to the growing antler. . . . Here was a 

 consequence of his experiment he had not at all fore- 



