622 PHILOSOPHICAL TRANSACTIONS. [aNNO 1795. 



day, when he died. The event of this experiment differs in nothing from the 

 former, than that the fate of the animal was suspended a Httle longer, but the 

 ultimate effect was exactly the same; therefore, in the first experiments, the ' 

 death of the animal is not to be imputed to the mere sudden deprivation of ner- 

 vous energy, but to its absolute loss. Wishing next to determine whether, by 

 lengthening the interval between the division of the 2 nerves a few days more, 

 the life of the animal could not be protracted to a greater length, or even saved, 

 I made another experiment. 



Exper. 3. Having divided 1 of the nerves of the 8th pair, and waited the 

 lapse of 9 days, I divided the other. The same symptoms came on now as in 

 the last experiment, but scarcely so violent. The only kind of food he would 

 take was milk, and that in small quantities, and this always produced great un- 

 easiness at the stomach, with symptoms of indigestion. In this state he conti- 

 nued 13 days, and then died, very much emaciated. From this dog having lin- 

 gered so long, I was beginning to entertain hopes of his recovery, and had that 

 eventually happened, I doubt much whether, even under the present uncertainty 

 of things, I could have resisted the temptation of ascribing such recovery to the 

 reproduction of the nerves; but the event put a stop to my speculation. 



I think I have now proved my first position, viz. that whether the 8th pair of 

 nerves be divided in immediate succession, so as to deprive an animal of their in- 

 fluence suddenly, or whether this deprivation be effected in a more gradual way, 

 the consequences are in the end equally fatal. I must next endeavour to avail 

 myself of this fact in the solution of the problem now before me. If the sub- 

 stance of nerve be reproduced, certainly a period longer than the above must be 

 necessary for this process; but to mark the precise point of time when the line 

 is to be drawn, would require the sacrifice of more animals than a question of 

 mere curiosity could justify. I must therefore content myself with giving a ge- 

 neral answer to the question, and inquire whether, by suspending the division of 

 the 2d nerve for a much greater length of time than was done in the last 2 ex- 

 periments, the existence of the animal could be preserved. 



Exper. 4. Another dog being procured, and one of the nerves of the 8th pair 

 divided, I allowed 6 weeks to elapse before the other was cut through. This 

 division of the corresponding nerve evidently deranged him; but in a much less 

 degree than in the former experiments. For some days he refused solid food, 

 but took milk; afterwards he ate solid food in small quantities; and near a 

 month had passed away before he fed as usual. The actions of the stomach 

 were for a long time evidently deranged, so that he was continually harassed with 

 symptoms of indigestion ; and 6 months had nearly elapsed before he recovered 

 his health, though during 5 months of the time he took his usual quantity of 

 food. Now, to what cause are we to impute his recovery ? The most probable 



