400 INNERVATION. [CHAP. XIII. 



substance occupying it sufficiently solid to keep the nerve in its 

 place. It does not seem to be mere fluid, like that distending the 

 intercapsular spaces. 



Henle and Kolliker have remarked,, that, where two corpuscles 

 are seated in succession on a single stalk (fig. 74, E), the pale axis- 

 cylinder regains its envelope of white substance from its point of 

 leaving the central cavity of the first, to its entering that of the 

 second ; and that in some cases, where the central cavity is bent 

 suddenly upon itself, so that it cannot be fairly surrounded by cap- 

 sules at the bend, it is there provided for a little way with white 

 substance. A very delicate layer of the same substance, just thick 

 enough to give a dark edge, occurs occasionally along the course 

 of the pale fibre. 



We have gone thus minutely into the structure of the Pacinian 

 corpuscles, because of the novel aspect in which they present the 

 constituent parts of the nerve -tube, placed in the heart of a system 

 of concentric membranous capsules with intervening fluid, and 

 divested of that layer which we regard as an isolator and pro- 

 tector of the more potential central axis within. The object of 

 this arrangement is quite unknown, and, in the present uncertain 

 state of our knowledge respecting the nature of the nervous 

 force, it seems almost idle to hazard guesses on the subject. 

 The apparatus of lamellae may either effect some change in the 

 enclosed nerve, by which the nervous centres in connexion with 

 it may be influenced as to their polarity ; or, on the other hand, 

 this apparatus may be the special instrument of some peculiar vital 

 agency, which the nervous filament is designed simply to bring 

 into communication with the nervous system. The latter view, to 

 which we incline, would bring these organs under the same category 

 with muscles, and the organs which develop light or electricity in 

 certain of the lower animals. Pacini has already drawn a com- 

 parison, in point of structure between them and the electrical 

 organs of the torpedo; and Henle and Kolliker favour this idea. 

 The well-known prisms of the electrical organs, according to Savi,* 

 consist of a congeries of very delicate transverse lamellae, on which 

 the nerve-tubes are distributed in a plexiform manner ; and, if w( 

 may judge from his figure, this plexus is not resolvable into loops, but 

 consists of true inosculations of the ultimate tubes, which also retain 

 the white substance of Schwann : but further researches are greatly 

 needed on this point. Wagner, with more probability, describes tl 



* Paul Savi, in Matteucci, loc. cit. 



