524 PHILOSOPHICAL TRANSACTIONS. [aNNO 1795. 



unsatisfactory in its result ; for there would still remain room for opposite opi- 

 nions : and while some would argue that these anastomosing filaments were be- 

 come evidently enlarged, others would contend that they had not suffered the 

 slightest change. Now I have already expressed my distrust of those decisions 

 which are founded on an appeal to the eye, seeing that anatomy has yet to ex- 

 plain by what mechanism or structure these organs perform their office ; and 

 because I have frequently heard opposite opinions on my own preparations. I 

 therefore prefer an appeal to the functions of these parts, and inquire whether, 

 in the experiment in which the dog survived the division of the 2d nerve of the 

 8th pair after an interval of 6 weeks, it was effected by the reproduction of the 

 first divided nerve, or in another way ? 



There are only 2 possible answers to such a question ; these are, that either 

 the functions of the stomach, larynx, &c. were carried on by anastomosing 

 nerves ; or that the united nerves had recovered their original importance. If 

 the first be contended for, this consequence ought to ensue, viz. that the 8th 

 pair should now be entirely useless, and both of them may be divided a 2d time, 

 without injuring any of the functions of the animal. If the last be granted, it 

 must of necessity follow, that the medium of union possessed the same proper- 

 ties as the original nerve. 



I have now circumscribed the field of inquiry, and have drawn the question 

 into so narrow a compass, that it is in the power of a single experiment to prove 

 either the affirmative or negative. If now the 8th pair be divided a 2d time in 

 immediate succession, and the animal sustain it with impunity, I conceive it 

 right to conclude, that the actions of those organs,, which originally were carried 

 on through the means of the 8th pair, are now performed by other channels, 

 and that the true substance of the nerve is not reproduced. But on the con- 

 trary, if the animal die in consequence of it, then 1 think it equally just to infer, 

 that the new formed substance is really and truly nerve, because we know of no 

 other substance which can perform the office of nerve. I shall rely then on the 

 following, and consider it as my experimentum crucis. 



Exper. 5. Having the dog in my possession on which I divided the 8th pair of 

 nerves \Q months before, I cut through both of them now, in immediate suc- 

 cession. The usual symptoms were immediately induced, and continued till the 

 2d day, when he died. After death I carefully dissected out these nerves, and 

 have preserved them as evidences of my success. I think I have now answered 

 the question I proposed to myself, and can affirm that nerves are not only capa- 

 ble of being united when divided, but that the new formed substance is really 

 and truly nerve. I forbear to make any animadversions on the experiments of 

 those who have formed conclusions contrary to my own : ta such I can only say, 

 that I shall always consider myself highly honoured in having the opportunity 



