4:44 NERVOUS SYSTEM. 



cells and nerves presiding over the nutrition of the muscular 

 system, or whether the phenomena observed cannot be ex- 

 plained by the partial degeneration of the ordinary motor 

 cells and nerves. 



There can be no doubt of the fact that the cells of the 

 antero-lateral columns of the spinal cord preside over mo- 

 tion, and that the stimulus' generated in these cells is con- 

 veyed to the muscles by the anterior roots of the spinal 

 nerves. It is a fact, no less definite, that when a muscle or 

 a part of a muscle is deprived of the motor stimulus by 

 which it is brought into action, its fibres atrophy, become 

 altered in structure, and lose their contractility. Starting 

 with these two well-defined physiological propositions, and 

 assuming that a few of the ordinary motor cells of the cord 

 are destroyed we will not call them trophic cells what 

 are the phenomena to be expected as a consequence of such 

 a lesion ? Reasoning from what we know of the physiology 

 of the nervous system, we should expect to find the follow- 

 ing conditions : 



The destruction of certain motor nerve-cells would cer- 

 tainly produce degeneration of the fibres to which they give 

 origin. This has been observed ; for, in this condition, the 

 anterior roots arising from the diseased portions of the cord 

 are atrophied. This occurs when any motor nerves are 

 separated from their cells of origin, and there is no necessity 

 of assuming the existence of special trophic cells or nerves. 



If a few of the motor cells be affected with disease, and 

 the degeneration be gradual and progressive, we should 

 expect progressive and partial paralysis of the muscles to 

 which their nerves are distributed. This paralysis, confined 

 to a limited number of fibres of particular muscles or sets 

 of muscles, would give the idea of progressive weakening 

 of the muscles, and the phenomena would not be those 

 observed in complete paralysis, produced by section of the 

 motor nerves. These are precisely the phenomena observed 

 in progressive muscular atrophy, preceding the paralysis, 



