564 NERVOUS SYSTEM 



Both the superficial and the deep reflexes often afford important infor- 

 mation in regard to diseases of the brain and spinal cord. 



The gray matter of the cord is not a single centre, but consists of a 

 number of centres connected with each other and with the brain. 

 Some of these have already been described in connection with the 

 history of various physiological processes, and others will be consid- 

 ered hereafter under appropriate heads. In addition to those already 

 described, are centres for defecation, at the fifth lumbar vertebra in dogs 

 (Budge), the erection-centre, in the lumbar region (Eckhard), and the 

 parturition-centre (Korner), at the first and second lumbar vertebrae. 

 Throughout the gray matter are a number of subsidiary vasomotor cen- 

 tres that are subordinate to similar dominant centres in the bulb. The 

 cord also contains subsidiary sweat-centres. 



