in Respiration. 3^9 



respiration might be completely disconnected, at least for a cer- 

 tain time, from the spinal marrow, the circulation might also be 

 completely disconnected from it. 



This animal is the fish. " I have shewn," said M. Flourens, 

 " by previous experiments, that the spinal marrow may be en- 

 tirely destroyed in fishes, without destroying the respiration; 

 seeing that it is no longer from the spinal marrow, as in the 

 other classes, but from the medulla oblongata alone, that in 

 these animals the nerves of the respiratory mechanism take their 



origin." 



The spinal marrow may equally be destroyed in fishes with- 

 out destroying the circulation. 



" I successively destroyed, in several carps and barbels, the 

 whole spinal marrow, without touching the medulla oblongata. 

 In all these fishes, the respiration and circulation continued for 

 a long time ; the motions of the trunk and appendages alone 

 disappeared, but the head and the region of the opercula con- 

 tinued to move as usual ; and the circulation still went on, even 

 at the extremity of the trunk, more than half an hour after the 

 total destruction of the spinal marrow." 



On the other hand, the author always found in the other 

 classes the circulation survive the destruction of all the parts of 

 the spinal marrow, which the respiration survived ; the destruc- 

 tion in birds, for example, of the lumbar portion, and that of 

 the lumbar and costal portions in quadrupeds. 



Thus, therefore, 1. There may be destroyed, without detri- 

 ment to' the circulation, all the parts of the spinal marrow, 

 which may be destroyed without detriment to respiration ; and 

 when the spinal marrow may be entirely destroyed without in- 

 juring the latter, as in fishes, it may be entirely destroyed with- 

 out injuring the former. 



2. The spinal marrow has therefore but a relative and van- 

 able action upon the circulation as upon the respiration. 



3. It is therefore especially because it exerts an influence 

 upon the respiration, that the spinal marrow influences the cir- 

 culation ; and it is by the same parts that it acts upon each. 



4. It is not in it, therefore, that the sole principle of the cir- 

 culation exists. 



