VOL. LXXXV.3 PHILOSOPHICAL TRANSACTIONS. 523 



one appears to be, that in the interval of 6 weeks the first nerve had been re- 

 produced ; so that the actions of those organs depending on this nerve, though 

 somewhat disturbed, were not suspended. But as the union of the 2d nerve 

 advanced, and the reproduction of the first became more perfect, the vital organs 

 gradually recovered their healthy state. 



I kept this animal IQ months, during thegreatest part of which time he performed 

 the office of a yard dog. And here it may be proper to observe, that in all the 

 experiments, the voice was totally lost on the division of the 2d nerve. This 

 effect anatomists will easily understand, from recollecting that the recurrent 

 branches of the 8th pair, which are the true vocal nerves, originate below the 

 part where the trunks of the 8th pair were cut through ; consequently those 

 nerves are themselves in efi^ect divided. Now it deserves to be remarked, that 

 his voice returned in proportion as his general health improved ; and in about 6 

 months he could bark as strongly as before, but the pitch of his voice was evi- 

 dently raised. 



From this experiment, I am strongly inclined to believe that there must have 

 been a true reproduction of the nerve ; yet I do not contend, that if the part of 

 union were examined by an anatomical eye, such reproduction would be very 

 evident. On the contrary, I am persuaded that anatomy can determine only 

 the presence and existence of an uniting medium ; but it is the province of phy- 

 siology to decide whether the medium of union possess the characters, and per- 

 form the function, of the original nerve. The evidence of reproduction, as 

 resting on this experiment, may not be sufficient to obviate certain doubts, which 

 reflections on this subject may probably suggest. There is a difficulty which 

 naturally presents itself here, viz. the possibility of the stomach and vocal organs 

 having received an additional supply of nervous energy from another source. 

 And to give an appearance of validity to this objection, it may be said that the 

 8th pair of nerves communicates energy to the larynx by means of the laryngeal 

 branch, and that this branch arises from the trunk above the part where the 

 division was made, and consequently its function received no interruption from 

 the experiment. Again, with regard to the stomach, another apparent objection 

 offers. This organ receives nerves from the great sympathetic, as well as the 

 8th pair ; and nothing hitherto advanced has tended to disprove, that the defect 

 of nervous influence from the division of the latter, has been supplied by greater 

 exertions of the former. Lastly, the familiar analogy of the vascular system, 

 where collateral branches are enlarged from the obliteration of a principal trunk, 

 tends further to give weight to these doubts. 



To remove these seeming difficulties by anatomical investigation, or by di- 

 recting my views to any changes that might be induced on the anastomosing ner- 

 vous filaments, would be an undertaking not less tedious in its execution than 



3 x2 



