684 DJR JAMES W. DAWSON ON 



change in the intellectual or psychical functions. That the cortical areas share in 

 the production of such symptoms cannot be doubted, but probably when these are 

 defined they are dependent upon the inhibition of the action of those cortical cells 

 which control the thalamic centres — the latter being intimately related to the 

 emotions and forming part of Langley's autonomic system. Such inhibition would 

 take place by the presence of sub-cortical areas in relation to the cortico-petal fibres 

 and to the presence of areas in the optic thalamus itself. Eeference has already been 

 made to the possibility that early psychical symptoms, such as restlessness, emotion- 

 alism, involuntary fits of laughter, may, together with the early transient palsies, be 

 referred to a functional change which precedes an anatomical, structural change. 



(xi) Ganglion cells. The ganglion cells in the grey matter of the spinal cord, 

 and in the analogous nuclei in the medulla oblongata and pons, retain for a long 

 time, even in the advancing sclerosis, their nucleus and chromophile granules. There 

 is considerable histological evidence to show that this accounts for the absence of 

 secondary degeneration in the anterior nerve roots, and, in part, for the remission of 

 the symptoms — for there is no reason to suppose that such cells do not function. 



The later varied changes in the ganglion cells must be ascribed to (l) the increas- 

 ing condensation of the sclerotic process ; (2) the absence of function ; and (3) the 

 associated somatic disturbances — the latter two factors will also influence the cells 

 throughout the non-sclerotic tissue. I have never seen in the cord an increase of the 

 satellite cells such as has just been described around the cortical ganglion cells. 



(xii) Axis cylinders. The persistence of numerous axis cylinders in the sclerotic 

 areas has been accepted as an axiom by most writers, and with this view I am in 

 entire agreement. Secondary degeneration is therefore not well defined, but it 

 affects a certain number of fibres. 



In the early areas the axis cylinders undergo a swelling, which may go on to 

 a granular disintegration, but those that survive the swelling, or have not shared 

 it, persist, in the advancing sclerosis, for a long time. This circumstance has been 

 held to explain (l) the absence of secondary degeneration ; (2) the remissions : the 

 gradual retrogression of the symptoms must be related to the resorption of the 

 fat granule cells, the swollen axis cylinders then diminish in volume, and impulses 

 would thus be able to proceed by means of the denuded axis cylinders — giving, 

 therefore, a remission of the symptoms ; and (3) the intention tremor — it is thought 

 that this impulse would be carried on irregularly in a broken or jerky manner 

 and would thus produce the oscillations which disturb the due execution of the 

 voluntary movements. It is supposed that this is effected in part by the absence 

 of the insulating myelin sheath, which allows of the diffusion of the impulse to 

 neighbouring axis cylinders and also by the pressure of the increasing glia. It 

 must be remembered, however, that though function is related in development to 



