1865.] Of the " Terminations" of Nerves in Papilla, $c. 259 



attention to the arrangement shown in these drawings, and especially to 

 that represented in this figure ; not that I would maintain that in the 

 finest fibres these three fibres are separated from one another or insu- 

 lated by a layer of white substance, but, on the contrary, I consider 

 that in many cases these fine fibres, although they may often be split in 

 the longitudinal direction, nevertheless in their natural state form almost 

 homogeneous fibres, the material of which may permit the passage of nerve- 

 currents in the different directions indicated. It is very probable that 

 the passage of the currents along precisely the same paths for a con- 

 siderable time may cause the decomposition of the nervous matter in 

 such a manner as to give rise to distinct lines, which might readily be 

 mistaken for separate fibres, and after a time lines of fibres in an ap- 

 parently transparent tissue would result*. At an early period of de- 

 velopment, nerves form a sort of thin expansion, in which the appear- 

 ance of fibres crossing one another in various directions may be after- 

 wards produced by the passage of the nerve-currents. Beneath the ex- 

 ternal investment of the common fly and many other insects, and beneath 

 the soft, delicate perivisceral membrane of mollusca, I have seen the most 

 beautiful and elaborate arrangement of apparent nerve-fibres of such a 

 character as to justify the above inference. 



In the cornea, that part of some of the nerve-fibres from which several 

 fine bundles radiate in different directions exhibits lines or fibres crossing 

 one another in every direction which the emerging fibres take. 



This subject is capable of much further elucidation, and is well worthy 

 of being considered in detail ; but in this Lecture I onlv allude to it cursorily 

 because it bears, in a most important manner, upon the question of unin- 

 terrupted nervous circuits, and affords an explanation of the manner in 

 which the complex arrangement which nerves ultimately exhibits is brought 

 about. 



Of the" termination" of nerves inpapillce and in special cutaneous nervous 

 organs, such as the papillae concerned in touch and taste, and in the 

 Pacinian corpuscles. 



Now in highly elaborate nervous organs like the papillae of the frog's 

 tongue, which are very minute, and situated comparatively close to one 

 another, we have an opportunity of studying, under great advantages, the 

 course pursued by the constituent fibres of a bundle of nerves. And 

 although even here it is not possible to follow a single fibre for any great 

 distance, a careful consideration of what can be demonstrated leads to the 

 inference that to every one of these papillae three sets of nerve-fibres are 

 distributed. 



I have always been able to demonstrate in the peripheral organs that I 

 have examined more than a single nerve-fibre; and where, as is almost 



* Indications of the Paths taken by the Nerve-currents, &c. : Churchill and Sons. 



