486 SPECIAL HISTOLOGY. 



for myself, I freely acknowledge the force of the reasons 

 adduced by the latter observer, which are based chiefly upon 

 the similarity of the fibres in question to the pale embryonic 

 nerve-fibres, inasmuch as that even in the adult, nucleated 

 nerve-fibres are met with in the olfactory nerve ; but I am com- 

 pelled, nevertheless, as before, fully to concur with Valentin, 

 as do also Bidder and Volkmann, and many others. My 

 reasons are the following: 1. The " fibres of Remak/' as may 

 be easily shown, arise from the sheath of the nerve-cells of the 

 sympathetic ganglia, and are continued in the nervous trunks, 

 surrounding the nerve-fibres arising from the ganglia. Now as 

 it is certain that these sheaths are a sort of connective tissue, 

 as is apparent also from the spinal ganglia, where they occur 

 in precisely a similar way, only more scantily and without 

 their being continued into the nerves, it follows that the 

 " fibres of Remak" can scarcely be anything else. 2. The 

 finest twigs of the spinal nerves also exhibit nucleated fibres, 

 in all respects like those of Remak, as for instance, those going 

 to the skin, &c.; with respect to which, as they are wanting 

 in the trunks of the nerves, there can be no question at all of 

 their not being nerve-fibres, 8. The quantity of the " fibres 

 of Remak" always diminishes towards the finest ramifications, 

 which could not be the case were they nerves. It is not, in- 

 deed, altogether correct, as stated by Valentin, that they are 

 not to be found in the finer intestinal nerves, for there can be 

 no doubt that they do exist there, though much more rarely 

 than in the trunks of the nerves, and are only to be brought 

 into view by compression. According to Remak (Mull. 'Arch./ 

 1844, p. 464), they also exist in the cardiac nerves of the 

 Mammalia ; although as far as I can perceive, only in the im- 

 mediate neighbourhood of the ganglia. Relying upon these 

 reasons, I continue in the firm persuasion that the nucleated 

 fibres in the sympathetic nerve of adult Mammalia are a form 

 of the neurilemma ; but I will not omit to remark, that I consider 

 it quite impossible to determine, in undeveloped nerves, what 

 is neurilemma and what young nerve-fibres. Thus in the 

 Rabbit, 2 — 6 months old, in the n. caroticus internus, not a 

 single developed nerve-fibre is to be met with, and apparently 

 nothing but " fibres of Remak/' although it is quite certain 

 that together with them, there must also exist the rudiments 



