722 DR ALEXANDER BRUCE AND DR JAMES W. DAWSON ON 
and SHERREN. ‘These observers state that the return of function and sensation in man, 
after secondary suture, coincides closely with the data obtained in animals for the re- 
appearance of new and fully-formed fibres. They think that earlier observers, who had 
deduced from a rapid return of sensation the presence of pre-formed fibres, had been 
led into error by the vague nature of certain kinds of sensation. 
BaRFURTH (1905) has carried out a series of sections of the sciatic nerve of the dog, 
and has come to conclusions almost identical with those of Berar. He criticises 
LANGLEY and ANDERSON’S acceptance of the presence of degeneration in the distal end 
after a second excision in the central stump as a proof of the ingrowth of fibres from 
the centre. He shows that this occurred in LancLtry and ANDERSON’s experiments only 
after 119-737 days, and remarks that surely some central fibres could in that time grow 
into the peripheral end. In his own experiments a second portion was excised 69 days 
after the first excision, and no trace of degenerated fibres could be found in the 
peripheral stump. His conclusions are that in favourable circumstances a regeneration 
of nerve fibres can take place in a peripheral nerve cut off from its central end, that 
this can go on to all the essential constituents of the nerve (axis-cylinder, myelin 
sheath, and neurilemma sheath), and that it takes place essentially by means of the 
nucleus of the sheath of Schwann cells. His closing words are too interesting to omit 
quoting: “ These nuclei can therefore be no plebeian mesenchyme cells, but are neuro- 
blastic elements of aristocratic ectodermic nature.” 
Lapinsky (1905) also supports the peripherist view. His contribution to this 
question is twofold: firstly, he shows that the regeneration in the central end is 
emphatically the same as that in the peripheral end—a point not quite so clearly brought 
out by previous writers; and secondly, he draws a marked distinction between autoch- 
thonous regeneration and neurotisation. In the former case the newly arising axis- 
cylinders remain unconnected with the centre, and microscopically they are very thin, 
show no fibrillar differentiation, have no resisting power, and soon degenerate; the 
myelin sheath also develops only incompletely and soon degenerates. In neurotisation 
the peripheral end is connected with the centre; there is therefore complete myelin 
sheath and axis-cylinder differentiation and complete functioning power. ‘‘ Obviously 
through this connection with the anterior horn cells the sluices are opened to the 
special stimuli which supply to the regenerated tissue its complete structure.” 
RaIMANN (1905) and Lugaro (1905) have used the most radical methods to exclude 
the influence of the centre. RaAIMANN, in newly born dogs, removed the spinal cord 
from the 2nd lumbar segment downwards together with the spinal ganglia as far as 
possible. In the single dog surviving, out of seven operated upon, in the sciatic nerve 
on the right side, which, of course, had been left untouched in its bed of tissue and in 
which therefore there could be no ingrowth of fibres from the neighbouring tissue, he 
found so large a number of fibres that they could not be explained except by regenera- 
tion. He drew the conclusion that the cells of Schwann’s sheath had produced a 
second nerve tube, which, however, he admits leads a transitory life. Lucaro, in adult 
