REPORT OF COMMISSIONERS OF INLAND FISHERIES. 149 



wounds the whole limb is usually autotomised, while in distal injuries 

 the limbs are quite frequently retained and the lost parts restored by 

 regeneration, — it follows that if abnormal structures do arise as the 

 result of the injury of normal and regenerating buds, it would be 

 most natural to expect that such abnormal structures would be most 

 frequently found on the distal segments. In our examination of 

 Faxon's and Bateson's lists, we have found that this is exactly the 

 case. 



Taking into account, then, these relations between the nature of 

 the injury, autotomy, and regeneration, it appears, therefore, that 

 the fact that the great majority of crustacean deformities occur on 

 the distal segments of the limb readily lends itself to the interpreta- 

 tion that they are the result of regenerative processes. 



d.YjThe Regeneration of Extra Legs Following an Artificial Splitting 

 of Nerves. 



3. A third point of importance is the effect of injuries which 

 involve a division of the nerve. Miss Reed ('04) in her study of 

 regeneration mentions certian results which she obtained in the 

 hermit crab by splitting the stump of the leg lengthwise after 

 autotomy had taken place. "In several cases after splitting the 

 stump, two extra legs appeared in a short while. Sections through 

 this region show that the nerve is split, one branch going to each leg. 

 It is probable that a new leg was developed at each end. of the split 

 nerve, since in all other cases where only one leg regenerated the 

 nerve shows no sign of any injury. In this case it is probable that 

 the nerve was not cut" (p. 315). Unfortunately, Miss Reed has 

 not described these regenerated extra legs, but this result is certainly 

 very suggestive ; it not only furnishes further evidence for the origin 

 of extra structures through regenerative processes, but also indicates 

 an important method for future experiments. In view of these 

 results one is also tempted to ask whether the rare case of triple legs 

 recorded by Bateson for the European lobster (No. 808) may not 



