268 Drs. Mott and Halliburton and Mr. Edmunds. [June 12, 



his observations on patients an experiment on one of the sensory nerves 

 of his own arm. This experiment gave an opportunity for the study of the 

 phenomena by a trained observer upon himself. He certainly experienced 

 no early return of function, and the date at which sensation did come back 

 coincides closely with the dates obtained in animals by physiologists for 

 the reappearance of new fibres. He has further made the interesting 

 suggestion that the first kind of sensation to return and which is of a vague 

 nature (termed protopathic) is associated with the activity of the fine 

 medullated nerve-fibres which replace the degenerated ones at an early 

 stage. Eeturn of protopathic sensibility begins about the eightieth day. 

 The more elaborate sensations and power to accurately localise them return 

 at a much later date, and this epicritic sensibility, as Head terms it, is usually 

 not perfect until many months, or even a few years, after the regeneration 

 started. By this time, as was shown by experiments on animals, the fine 

 nerve-fibres which subserve protopathic sensation are largely admixed with 

 a later growth of larger nerve-fibres, and he believes epicritic sensation is 

 subserved by these. He also postulates that the three kinds of sensation 

 (deep, protopathic, and epicritic) are related to different kinds of end organs 

 in the peripheral structures. It is not, however, necessary to enter more 

 fully into these results, for we have made no special study of the varieties 

 of sensation, nor have we in our experiments on animals kept them alive 

 for a sufficiently long period to enable us to see the fibres formed at very 

 late stages. 



After this introduction we propose to pass now to the consideration of our 

 own experiments. After the very conclusive researches of such investigators 

 as Langley and Anderson and of Cajal, it may seem rather a work of 

 supererogation to describe any more experiments which tell against the 

 autogenetic theory. We will only plead that every piece of confirmatory 

 evidence is useful if the upholders of that theory are to be convinced they 

 are wrong, and, moreover, in some directions our experiments are new, and 

 approach the problem in rather a different way from that followed by other 

 workers. 



We will describe them under the following heads : — 



(1) Experiments in which union of central and peripheral ends was 



prevented. 



(2) Experiments on transplanted pieces of nerve. 



(3) Experiments on the degeneration of regenerated fibres. 



(4) Experiments on the rate of medullation in regenerating nerves. 



(5) Experiments on the influence of stimulus on regeneration. 



In carrying out this work we should mention that the experiments on 



