58 Precentral or Motor Area [CHAP. 



Below the affected area, the extent and position of which is indicated in figure 4, 3 , the lamination 

 reassunied a normal appearance. 



It was interesting to find in this case that the groups of cells higher up, but below the buttress, which 

 may be looked upon as controlling shoulder and elbow movements, were, with rare exceptions, absolutely healthy. 



CONCLUSIONS DERIVED FROM THE EXAMINATION OF THE BRAIN IN THESE CASES 



OF AMPUTATION. 



It can scarcely be denied that the predominant change in the Betz cells in these cases, 

 and the change by which we are able to map out definite areas, is identical with the re- 

 active alteration Marinesco has described, at least that is the conclusion I have arrived at, 

 after a most minute examination of many hundreds of sections of the cortex, showing the 

 change ; after comparison of these with sections of the spinal cord from more or less recent 

 cases of amputation which have come under my own observation, and which show the change 

 to perfection in certain segments (these specimens were exhibited at a meeting of the 

 Liverpool Medical Institution several years ago) ; and after a perusal of the accounts and an 

 inspection of the drawings published by others who, in addition to Marinesco, have studied 

 the change. 



The question of the period of time which must elapse before the cells undergo this 

 particular alteration is of some importance, but unfortunately it is one upon which I cannot 

 write definitely on account of lack of information and experience. From experimental re- 

 searches we learn that changes arise in the anterior cornual cells of the spinal cord a very 

 short time 20 days after section of a peripheral motor nerve, but since before it reaches 

 the brain the retrograde alteration has a greater distance to travel and also a second neuron 

 to ascend, it stands to reason that the cortical changes must be of slower development than 

 the spinal. However, to settle this point, either some experiments on lower animals, or an 

 examination of more recent cases of amputation than those which have come under my notice, 

 will have to be carried out. I can only say that in my most recent case, namely, one in 

 which only two years had passed since the amputation, the change was seen to perfection, 

 and I therefore think that cases of this age are most suitable for purposes of localisation. 

 I also believe that, at this period, only those cells show degeneration which are connected 

 with the fibres contained in the severed nerve trunk, that is to say, the brain is free from 

 the confusing coexistence of changes of a purely atrophic nature, affecting cells for the control 

 of muscles above the level of the amputation, muscles which, without having their nervous 

 supply cut off, undergo wasting and shrinkage from want of use. 



Next concerning the duration of the alteration after it has once made its appearance, 

 I am convinced that a long period, not only months but even years, may pass by before 

 complete dissolution, which we are compelled to regard as the ultimate fate of the cells, super- 

 venes. This point is well exemplified in Case 3, for, notwithstanding the fact that at least twelve 

 years had elapsed after removal of the individual's legs, numbers of degenerated cells could 

 be seen persisting in the affected cerebral area, having only reached what one might call 

 the penultimate stage of retrograde destruction; furthermore, proving that not many had 

 completely broken up and disappeared, a cell count did not reveal a very pronounced numerical 

 reduction, compared with the normal brain. 



