720 DR ALEXANDER BRUCE AND DR JAMES W. DAWSON ON 
ends of divided nerves in rabbits—‘‘ nerves so divided that all regeneration from the 
central end was prevented by every possible means’—he found what he believed 
to be a limited peripheral regeneration of axis-cylinders. The neurilemma nuclei 
were proliferated and had formed chains, and definite young axis-cylinders had appeared 
in connection with these neurilemma nuclei which, in consequence, he looked upon 
as neuroblasts. The immature axis-cylinders tended to join on end to end with other 
axis-cylinders to form nerve fibres. Similar changes were found in portions of the 
sciatic nerves of rabbits divided, proximally and distally, by double sutures. These 
appearances were not seen until twenty days had elapsed after section or suture. 
These peripherally formed nerve fibres, or at least axis-cylinders, do not become 
myelinated or capable of functionating until they are joined on to the central segment— 
in other words, to their central and trophic neurones. 
FLEMING also accepts central regeneration and has often seen evidences of it, 
but he does not and cannot believe that central regeneration alone can ever explain 
the phenomena of secondary nerve suture. No explanation given by the centralists 
of those undoubted cases in which conduction of nerve impulses followed within 
a few days of secondary suture seems to him reasonable or possible. 
Langtry and ANpDERSON (1904) have objected to the conclusions of KENNEDY, 
BaLLaNce and Srewarr, and other autogenists, on the ground that there is no 
satisfactory evidence in their experiments that the peripheral end of a nerve, 
remaining ununited with a central end, had not united with the nerve fibres of 
the central end of other nerves cut through at the operation. They carried out 
a series of experiments to settle this point, and found that, when the peripheral end 
of a cut nerve was sewn into the skin or left lying amongst muscles, it made connection 
with the central nervous system by means of the nerves of the surrounding cut tissue, 
although it made no connection with its own central end. ‘They have demonstrated 
that all the medullated nerve fibres which reform in the peripheral end of a cut 
nerve degenerate when the nerves which run to the surrounding tissue are cut, or 
when the original nerve is again cut across-on the central side of the original point 
of section. They have further noted that the number of medullated nerve fibres 
found in the peripheral end of a cut nerve is very variable: a fact easily explained by 
the naturally varying connection with the central nervous system, but not explained 
by the autogenist view. It will be remembered that the difficulty in proving the 
absence of central connection with neighbouring nerves was the determining factor which 
led VuLpian to give up his earlier position. 
LaneLey and ANperson conclude from their experiments that the perinhen 
ends of cut fibres exercise a chemiotactic influence on the central ends and that this 
chemiotactic influence has numerous gradations, e.g. it is greater between fibres 
of one class, as it is well known that afferent fibres of one nerve can unite with 
the afferent fibres of another, but they cannot unite with the efferent fibres so as 
to produce any functional result. The evidence is still insuflicient to show whether 
