ORIGIN OF THE SPINAL NERVES. 555 



of the nerves on the other; the most superficial of the fibres 

 of the cord passing away, as the cervical nerves, and that thus 

 the whole were given off in succession, till the most internal 

 left it below, as the sacral and coccygeal ; thus making the 

 spinal marrow merely a large nervous cord, in which the cine- 

 ritious matter placed in its interior, appears no more to be 

 needed than in any other nervous trunk. At the upper part, 

 however, of the spinal marrow, where his imaginary lateral 

 column is placed, he believed the nerves destined to respira- 

 tion arose, and that these were capable of exercising their 

 functions occasionally, as in sleep and apoplexy, through the 

 influence of this column alone, without, and even in opposition 

 to the agency of the will. 



— Sir C. Bell however by his experiments, established an inter- 

 esting fact, that the function of respiration, even in man, is 

 partly an instinctive act, and thus opened a new and impor- 

 tant path of investigation. Anatomists following in his train 

 of observation, have shown the cineritious nucleus of the 

 spinal marrow, to be the source and origin of many of the 

 fibres of the spinal and cerebral nerves, as he supposed the 

 lateral column of the medulla oblongata to be to the respira- 

 tory. Meckel and Cruvielhier assert that this appears to them 

 to be the case ; Ollivier and Gall, have asserted it more boldly. 

 Mayo and Marshall Hall,* seem to have proved it by their 

 experiments, in which they separated the cord from the brain at 

 various heights, and observed that nerves which came off from 

 below the place of separation, running to the eye, nose, anus, 

 etc., were still found, on mechanical irritation, to possess a sort 

 of instinctive sensation, and to be capable of producing com- 

 bined involuntary muscular movements to a certain extent. 

 More recently Mr. Graingerf of London, by adopting an 

 improved method of investigating the origin of the nerves, 

 has succeeded in tracing a part of the fibres of the anterior 

 and posterior roots of all the spinal nerves, into the cineritious 



* Vide Mayo's Physiology, and M. Hall on the Nervous System. 



f On the Structure and Functions of the Spinal Cord. London, 1838. 



