REGENERATION 271 



being simultaneous arrest, not to say loss, of function. Every- 

 thing indicates that of all the cells of the body the neurones are 

 those endowed with the longest life period. 



During foetal or larval life, prior to the attaining of full 

 function, such proliferation has been recognized (Barfurth), or 

 otherwise the incompletely differentiated nerve-cells may take 

 part in the regenerative process ; though it may be considered 

 an open question whether the new development of neurones in 

 experiments upon the spinal cord of the larval newt and other 

 amphibia is the result of proliferation of developed neurones or 

 of mother cells. 



That such mother cells must exist even in the human nervous 

 system has been forcibly brought home to me by a study of 

 certain sections of the spinal cord to which Dr. Shirres, 1 working 

 in my laboratory at the Royal Victoria Hospital, recently called 

 my attention. 



These sections are from a case of porencephalus in which 

 apparently, from all indications, the atrophy and disappearance 

 of practically the whole motor area in the left hemisphere dated 

 from the last month or two of foetal life. Despite this practically 

 complete loss of the entire motor area on the left side, the result- 

 ing evidence of paralysis and disturbance of function were little 

 more than a relatively slight want of development of the bones 

 and muscles of the right side of the body together with paresis 

 of the musculature of the right hand. In the cord the difference 

 between the two motor tracts is most marked, there is entire 

 absence of the crossed pyramidal tract on the left side, of the 

 direct pyramidal tract on the right, and, corresponding with this, 

 there is a most marked atrophy of those groups of cells towards 

 the periphery of the anterior horn of the grey matter on the 

 right side, which everything indicates as being connected with 

 the crossed pyramidal tract and being what I may term the 

 spinal motor centres for the upper extremity. But in sections 

 in which this atrophy is most marked there is a distinct increase 

 in the number of ganglion cells in the deeper and more central 

 areas of the grey matter ; here the number of cells is much above 

 the normal, the cells are large and more numerous than those 

 of the left side of the same section. 



For our present purposes it is clear that these abundant cells 



1 [Studies from the Royal Victoria Hospital, Montreal], No. 1, 1901. 



