Manchester Memoirs. Vol. xlii. (1898), No. \%. 13 



It is only by means of this coarser visible material that 

 we get ocular evidences of the work of nutrition. Hence 

 it is in the perikaryon and the clustering dendrites, not in 

 the long drawn-out axon that we get visible indications of 

 how the nutrition of the cell is influenced by circum- 

 stances, by rest or activity, by disease or by toxic 

 agents. But it is the evidence only which is thus limited, 

 not the effect. The work of the laboratory of the 

 perikaryon is carried on for the good not of itself only, 

 but of the whole unit, for the good not of the part close 

 round the nucleus only, but of the whole stretch of axon 

 or dendrite down to its furthest terminal twig. Our 

 knowledge of the intimate nature of this work of nutrition, 

 of the building up and clearing away of the exquisitely 

 organized, that is, molecularly organized, material which 

 alone does " nervous work " is of the scantiest ; but it is 

 at least obvious that the processes of this nutrition are 

 complex. While in the nutrition of a distant portion of 

 the axon, part of the work is being done on the spot, part 

 is being done in some way or other by the perikaryon. 

 More than this we cannot at present say. 



Moreover, not only is the axon dependent on the 

 perikaryon, but the latter also is dependent on the former. 

 When an axon is cut across, the portion in connection 

 with the perikaryon and nucleus does not degenerate and 

 perish like the peripheral portion. Nevertheless, the 

 perikaryon, indeed, the whole remaining nerve cell, does 

 undergo visible structural changes if it be deprived of the 

 nerve fibre which springs from it. This takes place not 

 only when an afferent fibre is cut away, in which case the 

 changes might be supposed to result from inaction, from 

 the absence of customary impulses passing towards the 

 nucleus along the fibre, but also when an efferent fibre is 

 cut away, in which case the cell within the central nervous 

 system is still subject to the influences which ordinarily 



