THE NERVOUS SYSTEM. 655 



the sympathetic supply for these glands passes along with the vaso- 

 motor fibres from the cervical splanchnic (or sympathetic trunk), and 

 superior cervical ganglion; while the cerebro-spinal supply comes from 

 the rami viscerales of the cranial nerves in conjunction with the vaso- 

 dilator fibres. 



Central Origin of the Rami Viscerales. There appears to be the 

 strongest presumption that the white rami of the thoracic region arise 

 in the spinal cord in, or are connected with, the cells of the posterior 

 vesicular column of Clarke. This conclusion is based upon the fact that 

 these special cells are found in the three regions already mentioned, and 

 in those only where the white rami of fine medullated fibres exist, viz., 

 in the cervico-cranial regions, in the spinal accessory, in the thoracic 

 region, and in the sacral region. But it is probable that the fibres are 

 also connected with the cells of the lateral horn of the gray matter of 

 the spinal cord, and its representative in the medulla, the antero-lateral 

 nucleus of Clarke. 



In a paper supplementary to his first account of the sympathetic 

 system, Gaskell traced the nerve fibres of the anterior nerve roots to the 

 various groups of nerve cells in the spinal cord thus: (i.) Efferent 

 nerves to somatic muscles arise from group of cells of anterior cornua; 

 (ii.) efferent nerves to striated splanchnic muscles from cells of the trac- 

 tus intermedio-lateralis. (iii. ) Anabolic or inhibitory nerves to glands, 

 muscles of viscera, and vessels of splanchnic system from cells of Clarke's 

 column; (iv.) motor nerves to visceral muscles from solitary cells at the 

 base of the posterior cornu ; and (v.) motor or catabolic nerves to glands 

 and vascular muscles from small cells of the lateral cornu. 



Structure and Functions of the Ganglia. The sympathetic 

 ganglia all contain (1.) nerve-fibres traversing them; (2.) nerve-fibres 

 originating in them, (3.) nerve or ganglion -corpuscles, giving origin to 

 these fibres; and (4.) other corpuscles that appear free. In the sym- 

 pathetic ganglia of the frog, ganglion- cells of a very complicated struc- 

 ture have been described by Beale, and subsequently by Arnold. The 

 cells are inclosed each in a nucleated capsule: they are pyriform in shape, 

 and from the pointed end two fibres are given off, which gradually 

 acquire the characters of nerve-fibres; one of them is straight, and the 

 other (which sometimes arises from the cell by two roots) is spirally 

 coiled around it. 



According to Gaskell the functions of the main sympathetic ganglia 

 are the following :(!.) They effect the conversion of medullated into 

 non-medullated fibres; (2.) They possess a nutritive influence over the 

 nerves which pass from them to the periphery; (3.) They increase the 

 number of fibres at the same time as they cause the removal of the 

 medulla. As regards their possession of the usual properties of nerve- 



