1906.] The Structure of Nerve-fibres. 19 



cell-bodies of secretory cells, or in the bodies of nerve-cells, are no doubt 

 elicitable by similar means, which also have the same significance. It is 

 possible that Nissl granules are of this order of importance. Failing definite 

 evidence upon which to make any assertion, it must at least be said that 

 the well-known appearances accompanying " chromatolysis " are extremely 

 suggestive in character. They would seem to be the consequences of such 

 changes in osmotic pressure as would result from the sudden liberation of 

 salts into solution. 



Neurofibrils. 



It is now possible to deal with the phenomena observed in that tract of 

 the teased nerve-fibres which corresponds with Bethe's indifference point 

 and its granules. In teased nerve-tibres this region is naturally much more 

 extended, since the polarising " injury current " has a comparatively small 

 value and the changes in the intrapolar region are more gradual. Throughout 

 the whole of this region dense granule formations occur, and these are of 

 such a striking appearance when examined with high powers of the 

 microscope as to absorb a major share of attention. In my own case their 

 fascination left me at first with scant respect for the polar changes described 

 above. To a certain extent this interest is justified when it is considered 

 as the region least involved in polar changes, and altered, therefore, only 

 from the " normal " resting condition in so far as it is involved in the 

 transmission of an electrical current. For the present, however, it is 

 sufficient to deal with the light which these granule formations throw upon 

 the artificial structures known as neurofibrils. 



In a previous communication I reported the fact that in nerve-fibres 

 teased in saline solution I had neve*r seen structures bearing any very close 

 resemblance to the neurofibrils described as making their appearance in 

 nerve-fibres " fixed " and stained in special reagents. Since making this 

 statement I have, however, seen structures which cannot be described as 

 granules, since their length is considerable and their thickness much too 

 minute, and which yet cannot be called "neurofibrils," since they are too 

 short, too irregularly arranged, and since they anastomose. The resemblance 

 which they bear to the "neurofibrils" described as found in fixed nerve- 

 fibres is very much that borne by the anastomosing networks of fibrils 

 described as structural components of some nerve-cells. Fibrils such as 

 this I have only seen in some few out of the many nerves that I have teased. 

 Much more frequent, but still only of comparatively occasional occurrence, 

 are structures conveniently classed as bacillar granules, shorter but more 



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