THE SPINAL MARROW AND ITS FUNCTIONS. 141 



Its action, however in such cases is much weakened. That 

 the heart is, however, in some measure influenced by the spi- 

 nal innervation, must be admitted. 



16. /'What is called the capillary circulation, or that in the 

 small vessels, is much under the influence of the spinal mar- 

 row. ) It is found that when any part of it is destroyed, the 

 blood does not, circulate in the small vessels which derive 

 their nerves from the portion destroyed. In these cases, the 

 skin becomes purple, and dry ; perspiration ceases, the cuti- 

 cle peels off, and the part becomes sensibly colder. The 

 whole nervous system, however, is concerned in the produc- 

 tion of animal heat. 



17^ Digestion is to a considerable degree under the influ- 

 ence of the spinal cord^ /In all cases of diseases of the spine, 

 the appetite is poor, and the digestive powers weak. Colic 

 and dyspepsia are frequent attendants upon such complaints. 

 If the eighth pair of nerves be divided, the stomach is imme- 

 diately paralyzed, and digestion interrupted.} This shows 

 that the stomach depends for nervous influence on the me. 

 dulla oblongata, and that it is derived through the medium of 

 the par vagum. 



18. The spinal marrow exerts an important influence over 

 the kidneys, more so perhaps than over any of the abdominal 

 viscera. Some physiologists also think that it presides over 

 the functions of nutrition. What seems to confirm this 

 opinion, is the fact, that in the Crustacea, insects, and worms,- 

 which have the power of speedily reproducing any part that 

 is cut off, the spinal marrow preponderates over every other 

 portion of the nervous system. Nutrition is known to depend 

 chiefly on the influence of the great sympathetic nerve, but 

 its connections with the spinal marrow are so numerous and 

 intimate, that there can be little doubt, it derives a consider- 

 able portion of its nervous energy from the latter. The fol- 

 lowing cut represents the left side of the brain and spinal 

 marrow, shown by making a section of the cranium and the 

 spinal column, and removing the dura mater. 



