878 



PACINIAN BODIES. 



One of the nerves of the palm with the corpuscles 

 appended, and of natural size. After Henle atul 

 Kolliker. 



To the naked eye they here present a beautiful 

 semi-transparent pearly lustre, with a whitish 

 opaline streak along the axis, resulting from the 

 greater proximity and density of the series of 

 internal capsules. In some animals of this 

 species they have appeared to me almost want- 

 ing. It is remarkable that in no instance have 

 they been detected in connection with nerves 

 purely motor, nor, it is affirmed, on the fifth 

 nerve or the glosso-pharyngeal. 



The stulk consists, as has been said, of a 

 production of the neurilemma enclosing a single 

 nerve-tube. It sometimes happens that there 

 are two nerve-tubes, but then there are two 

 corpuscles on the single stem, either in close 

 apposition, or actually enveloped by a few cap- 

 sules common to both. The nerve-tube in the 

 stalk is undulating, and being accompanied by 

 white fibrous tissue is easily distinguished by 

 its peculiar structure. The artery and vein 

 supplying the corpuscle are also included in 

 the stalk. x 



The channel which the stalk occupies in its 

 passage through the capsules, is conical and 

 comes to a termination at the proximal end of 

 the innermost capsule. It is furnished with a 

 membranous wall, with which the fibrous tissue 

 of the stalk is united on the inside and the 

 several capsules on the other, and by this means 

 the intercapsular spaces are preserved closed, 

 and their fluid retained. This wall usually 

 presents irregularities of outline, and often a 

 cellular appearance, where the capsules, and 

 especially the inner ones, join it. It is perfo- 

 rated by the minute vessels as they enter some 

 of the intercapsular spaces (Jig. 482). 



The capsules themselves are inelastic mem- 

 branes, analogous probably to the white fibrous 

 tissue, and furnished with clear transparent 

 nuclei that project chiefly on the inner surface. 

 This is true of all the capsules, but in the outer 

 system or those thicker and stronger ones be- 

 tween which fluid intervenes, there is evidence 

 of a double wall ; for in addition to the clear 



double line which distinguishes all, these pre- 

 sent also on their outside, when seen edgeways,. 

 a series of dots, which indicate a system of 

 transverse or circular fibres, and in fact the 

 corpuscle, when brought into focus, shows no 

 other fibrillation than this transverse one. Al- 

 most all appearance of a fibrous texture is re- 

 moved by acetic acid, so that the yellow or 

 elastic fibre does not appear to form any portion 

 of the capsular membranes. The outermost 

 capsule, indeed, is invested with both the 

 elastic and the inelastic fibres, but these are to 

 be regarded as belonging rather to the areolar 

 tissue in which the corpuscles are imbedded, 

 than to these organs themselves. The capsules 

 are united together by the wall of the channel 

 of the stalk. They are also joined here and 

 there by partial membranous septa passing 

 directly or obliquely across the intercapsular 

 spaces, and which seem to be of the same na- 

 ture as the capsules themselves. Pacini de- 

 scribes further a union of the capsules at the 

 distal end in the axis of the corpuscle, which is 

 denied by Henle and Kolliker to exist. I 

 have had, however, unequivocal evidence of its 

 existence, especially between the inner capsules, 

 when they have been artificially distended by 

 water, although it often appears to cease to- 

 wards the surface. When the end of the cap- 

 sules is bent on itself, the line of this intercap- 

 sular union is less easy to trace. 



The small artery supplying the corpuscle 

 subdivides in the channel of the stalk into its 

 three, four, or more capillaries, which pierce 

 the wall and enter the intercapsular spaces. 

 After advancing in these for a variable distance 

 they form loops, and return by a similar route 

 to the small corresponding vein. In the larger 

 corpuscles I have seen a little bunch of vessels 

 formed near the further end by some of these 

 capillaries. In most cases a single capillary 

 accompanies the nerve-tube as far as the central 

 capsule, and then passes for some way upon its 

 wall, sometimes in a spiral direction. If a 

 perfectly fresh corpuscle from the mesentery of 

 a cat be examined before the, biood has drained 

 ofT, the addition of a little water will occa- 

 sionally induce a rapid movement of the con- 

 tents of these minute vessels under the eye of 

 the observer, by gaining entrance to their 

 interior; and few objects are more beautiful 

 than the miniature circulation thus artificially 

 brought about for a brief period. The capil- 

 laries have their proper walls, furnished with 

 nuclei. 



The central cavity, in size, and particularly 

 in shape, is liable to much variety. It has 

 been already stated to be not unfrequently bent 

 upon itself towards the further end ; sometimes 

 it is bifurcated, or, more correctly, branched, 

 the offset then passing in a recurrent course 

 either from the commencement or the middle 

 part of its length. In this case the branch is 

 surrounded by the same series of internal close 

 capsules, and external ones separated by fluid, 

 which encircle the principal cavity, only accom- 

 modated to the irregular conformation. How- 

 ever the central cavity is modified, it always 

 retains its transparent character, and on its inner 



