MINUTE ANATOMY OF THE OLFACTORY NERVES. 213 



cessfully coloured specimens the processes of the olfactory cells 

 also become distinctly stained, whilst the nucleus remains 

 pale and transparent. I possess a preparation made from a 

 tortoise, unique amongst many hundred sections, in which the 

 direct passage of the nerve fibrils into the epithelial layer is 

 observable. In this instance branches arise from the deeper- 

 lying trunks of the olfactory nerves, and run nearly vertically 

 towards the epithelial layer. These branches are fibrillated, 

 and are beset with nuclei subdividing as they continue their 

 course to the attached surface of the epithelium ; they here 

 break up into fibrils and extremely fine fasciculi, which spread 

 out horizontally for a very short distance, like a fan, and then 

 run perpendicularly, but in an irregularly sinuous manner, 

 into the epithelial layer itself, where they may be followed as 

 far as to the nuclei of the olfactory cells. M. Schultze's hypo- 

 thesis would become matter of fact if in the chloride of gold 

 we possessed an agent that stained nervous elements alone, and 

 was less capricious in its action, so as to produce no illusory 

 appearances. We find also, as mentioned above, in the epi- 

 thelial layer of the olfactory region, the peculiar cells which 

 very closely resemble the forked cells of Engelmann. Whether 

 we should regard these as constituting the terminations of the 

 nerves is questionable. 



In many instances appearances are presented which render 

 it quite evident how the secondary fibrils, united into fasciculi, 

 penetrate into the epithelial layer, and ran for a considerable 

 distance outwards between the epithelial cells, which is obvi- 

 ously suggestive of their terminating with free extremities 

 (tig. 338, 0). This is in apparent contradiction to what has 

 been said in our earlier statements respecting the termination of 

 the nerves, but the opposition is only apparent. If we admit 

 that, as I have satisfied myself with the adoption of every pre- 

 caution, the olfactory region is sensitive, if we further consider it 

 to be highly probable that sensibility and smell are communicated 

 by separate nerves, it immediately suggests itself to consider 

 the free nerve ends I have observed as belonging to the fibres 

 of simple sensation. Max Schultze has moreover already ob- 

 served medullated between the non-medullated fibres. 



The question in regard to the relation of the olfactory fibrils 



