48 Precentral or Motor Area [CHAP. 



is, it is only fair to Gudclen to mention that he, many years ago, initiated a number of 

 valuable researches in the same direction, and that the form of atrophy, which many still 

 associate with his name, and which formed the keynote of his work, is identical with the 

 change we are now considering. As other writers have reviewed the whole subject of retrograde 

 degeneration, a histological account is not called for here ; nor is it necessary to consider 

 anything further than the change as it affects the nerve cell. This change is perhaps best 

 known by Marinesco's name " reaction a distance," and it differs from the Wallerian reaction 

 in ascending the physiological stream of conduction and affecting the cell at the central end 

 of the cut nerve, instead of descending and attacking the peripheral end. The condition is 

 described in Marinesco's words as follows. 



" La premiere alteration, apres la section d'un nerf, est la disintegration ou, comme je 1'ai appelee, la 

 chromatolyse des corpuscules chromatiques. 



Cette lesion commence tout pres du cylindraxe. La chromatolyse pent gagner tout le corps de la cellule 

 nerveuse, mais, une chose essentielle a noter, c'est que le noyau qui, a 1'etat normal, occupe le centre de 

 la cellule, emigre a ce moment vers la peripherie. 



Quand la plus grande partie de la substance chromatique est ainsi desintegree, le centre de la cellule 

 presente un fond plus ou moins uniforme dans lequel sout disseminees de fines granulations. 



Cette disintegration de la substance chromatique permet quelquefois d'entrevoir dans le cytoplasma un 

 reseau trabeculaire, qui n'est autre chose que la substance achromatique, organises, c'est-a-dire celle qui se 

 continue directement avec les fibrilles du cylindraxe. 



Les modifications de reaction h distance que je viens de decrire peuvent, dans une deuxieme phase, 

 retroceder, et la cellule recupere un aspect normal ; cette deuxieme phase est la phase de reparation. Pour 

 connaltre exactement ce qui se passe dans la cellule nerveuse pendant la phase de reparation, il faut laisser 

 les animaux vivre pendant un, deux, trois ou quatre mois. On voit bien alors que la cellule, avant de 

 revenir k son aspect normal, presente une hypertrophie considerable, qui s'accroit jusqu'a 90 jours apres la 

 section, et qui interesse k la fois le volume general de la cellule et celui des elements chromatophiles. 

 Ceux-ci acquierent de grandes dimensions, se coloreut d'une rnaniere plus fonc^e ; ainsi la cellule presente, 

 d'une part, une augmentation de volume, et d'autre part, une coloration plus intense." 



The " phase de reparation " last-mentioned seems to be a manifestation of nerve re- 

 union ; for in accordance with our experience of the changes in the human spinal cord in 

 cases of limb amputation, destruction and total disappearance seem to be the final ending 

 of the affected cell, and I make this statement in full knowledge of the controversies which 

 surround the question. 



Without differing materially from the above, the accounts given by others show that 

 this reaction varies considerably in accordance with different conditions, for example, the 

 age and variety of the animal experimented with, the nature of the lesion and its distance 

 from the centre. 



So far I have only alluded to the change as it affects cells in the spinal cord or 

 cranial nerve nuclei ; I have next to mention that changes of an analogous description have 

 been found by Marinesco, and others, in the cortex cerebri ; and, what is to us of more 

 importance, such alterations have been observed, not as a product of experiment in lower 

 animals, but as a result of natural lesions in the human being. In the first place, Marinesco 

 examined the Rolandic area in six cases of hemiplegia, due to more or less old-standing 

 lesions of the internal capsule, and, in the paracentral lobule, on the same side as the 

 destructive focus, he invariably found alterations confined to the giant cells. These he 

 describes as follows. 



