1 66 Journal of Comparative Neurology and Psychology. 



This much, at least, is clear, that the nervous system is 

 not made up of structural elements (neurones) in the same sense 

 that a house is built up of bricks or even that the liver is made 

 of cells. The functional unit of the nervous system is the con- 

 duction path or functional system of neurones, and for aught 

 that we know to the contrary, the same neurone may be a 

 member now of one functional circuit, now of another totally 

 different. This is suggested, not only by the familiar anato- 

 mical connections of the associational centers and simpler re- 

 flex stations of the brain, but also by some more recondite 

 phenomena, such as the vicarious functioning of one cortical 

 area after injury to another. 



Still more striking in this connection are the cases of sub- 

 stitution of function after peripheral nerve anastomosis, such as 

 that recorded by Gushing and referred to in our last issue. 

 After traumatic destruction of the facialis root and resultant 

 paralysis, the central end of the spinal accessory nerve was 

 sutured on to the peripheral facialis and a successful union 

 effected. There resulted total permanent paralysis of the 

 trapezius and sterno-mastoid muscles and almost perfect restora- 

 tion of facial symmetry both at rest and (less perfectly) in the 

 facial movements. 



Experimental cross-suturing has long been practiced on 

 lower animals and Langley has recently been reporting in the 

 Journal of Physiology a series of such operations, especially 

 upon the cervical sympathetic. In a case reported upon in 

 February of this year the fifth cervical nerve in a kitten was 

 sutured to the cervical sympathetic and functional union re- 

 sulted. After 187 days, stimulation of the fifth cervical nerve 

 caused the usual effects produced by stimulation of the cervical 

 sympathetic. Since the fifth cervical root contains no pre- 

 ganglionic sympathetic fibers it follows that "certain somatic 

 nerve fibers are capable in favorable circumstances of making 

 functional connection with sympathetic nerve cells." 



It is evident that such remarkable changes in peripheral 

 connections must result in profound changes in the central con- 

 duction pathways, and that too probably without the loss of 



