500 GENERAL ANATOMY. 



certain distance from the extremity, the nervous properties 

 and structure. The time necessary for the complete re-es- 

 tablishment of thestructure and functions is not exactly known; 

 it has been certainly exaggerated by those who have advanced 

 that several years are required: it may be estimated at about 

 six weeks or two months. 



789. The section of the pneumo-gastric and trisplanchnic 

 nerves united, as they are in the dog, produces constantly 

 death, when it is done on both sides at once. It is upon these 

 nerves that the re-establishment of the functions and the sepa- 

 ration of the tissue may be studied simultaneously, according 

 to the experiments of Cruikshank, Haighton, and our own. 



The following is what we have seen take place in this sec- 

 tion, repeated at different intervals. 



Having cut, on the same day, the two pneumo-gastric nrvese 

 in two different dogs, one died thirty hours after the operation, 

 the other more than sixty-six hours after this double section. 

 Another animal, after an interval of nine days between the 

 two sections, died in the night of the fourth and fifth day. In 

 a fourth, the second section having been made at the end of 

 twenty-one days, death took place only on the twenty fifth day, 

 after this second section. Finally, upon another animal, the 

 second section was made thirty-two days after the first, and 

 the animal survived an entire month. At this period, that is 

 to say, two months after the first section, we found the nerve 

 which was first divided, completely reunited. This dog fell 

 under an empyema which developed itself in the left cavity 

 of the chest. Finally, Haighton cut the second pneumo-gastric 

 nerve six weeks after the first, and the animal survived nine- 

 teen months, after which time it was killed. It has been pre- 

 tended that the nervous action, in the same manner as galvan- 

 ic action, might re-establish itself across a substance differ- 

 ent from the nervous tissue, as a fluid or moist cellular tis- 

 sue; it has been pretended, als6, that the nervous action might 

 take place at a distance, and pass over the interval which 

 exists between the ends of the nerve; it has been pretended, 

 finally, that the re-establishment of the functions might take 

 place by anastomosing branches. If it was by the one or the 



