752 REPORT—1904. 
functions. At present there are two main ideas of structure, one often called the 
neurone theory, according to which the nervous system is made up of a multitude 
of neurones or cells which have no connection with one another, and the fibrillar 
theory, according to which the nervous conducting part consists of minute fibrils 
joined together here and there into a network. Professor Langley argued that 
whatever view is taken of the structure of the nervous system, the facts of de- 
generation of nerves show that it is made up of a number of trophic units, and that 
the theory of trophic units held whether the unit consisted of one or of a hundred 
cells, and whether the units were in continuity with one another or only in con- 
tiguity. 
< Assent point which seemed certain was that the properties of the central 
nervous system required for their explanation some structure not present in the 
peripheral nerves. This structure might be, in part, the nerve-endings of the 
trophic units, but in part it must be referred to the nerve-cells, which, in fact, 
consisted of different protoplasm from that of either nerve fibres or nerve-endings. 
If the fibrillar theory were true, there were facts which showed that the fibrils 
must be different in different parts of their course. This was illustrated by the 
action of nicotine and of other poisons on the different parts of the nervous system. 
With this modification the fibrillar theory simply transferred to a part of the cell 
functions which were commonly supposed to belong to the whole. But it could 
not be regarded as certain that there were any fibrils at all in the nerve cell, for 
the microscopic appearances varied considerably according to the method of pre- 
aration. 
‘ A point which was much contested was the question whether the trophic units 
were continuous with one another or not. This point was not of great physio- 
logical importance, but physiological facts were best explained on the assumption 
that the units were contiguous but not continuous. 
The last point considered was whether the unit consisted of a single cell or of 
many cells. The study of the development of nerves had led different observers 
to entirely opposite conclusions. Experimentally, the question was of interest in 
connection with the regeneration of nerves. Numerous surgeons had found new 
nerve fibres in the peripheral ends of cut nerves, but their observations failed to 
show that some central connection had not been established. In some recent 
experiments made by Professor Langley, in conjunction with Dr. Anderson, it was 
found that without a single exception the new fibres had become connected with 
the central nervous system. The balance of evidence was, then, against the 
occurrence of autogenic regeneration and in favour of the unit consisting of a 
single cell. 
Dr. A. Hill said that he was entirely prepared to give his approval to the 
neurone theory as defined by Professor Langley, but he objected that this was 
merely a statement of the cell theory, and did not require the special title given 
to it by Waldeyer. He was inclined to think that the more light we gained on 
this subject the more should we find that Bethe’s view was correct. Apathy has 
shown a network of neuro-fibrille in nerve cells of invertebrates. This network 
is easily shown, and is beyond all doubt a structure existing during life. In the 
spinal ganglion cells of vertebrates a somewhat similar appearance is obtainable. 
Itwas easy to make preparations of vertebrate nerve cells in which fibrille were 
indisputably present, but how far this appearance was due to reagents it was 
impossible to say ; but there was a strong probability that the net arranged itself 
about an existing system of fibrils. The connecting-link appeared to him to be 
the ‘thorns,’ and it was a remarkable fact that the spacing of the thorns cor- 
responded to the spacing of the pericellular network. Far as we were from being 
in a position to form a conclusion on this subject, it was not impossible that 
neuro-fibrillz, Golgi’s net, and thorns form a system of conducting fibrils of ex- 
treme tenuity and almost infinite complexity. 
Professor Graham Kerr gave an account of the results of his researches on 
the development of the nerves in Lepidosiren. His first studies on the mode of 
growth of the nerves in these animals seemed all in favour of His’s view that the 
nerves developed as outgrowths from the spinal system; but more extended 
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