cliv 



NERVOUS SYSTEM. 



lemma, but at the same time has its own proper wall, round which, on the outside 

 the capsules are attached. Whichever view may be correct, the capsules are, as it 

 were, strung together where the nerve passes through them, and each intercapsular 

 space, with its contained matter, is shut off from the neighbouring ones. The 

 nerve-fibre, the disposition of which must now be noticed, is single as it runs along 



Fig. XG. 



Fig. XO. A, MAGNIFIED VIEW OP A PACINIAN BODY PROM THE MRSENTERY OP A CAT, 

 showing the lamellar structure, the capsules with their nuclei, the inner and closer series of 

 capsules appearing darker in the figure, the nerve-fibre passing along the peduncle, and 

 penetrating the capsules to reach the core in the central cavity, where it loses its strong, 

 dark outline, and terminates by an irregular knob at the distal and here dilated end of 

 the cavity. Connective tissue (neurilemma or perineurium) and blood-vessels are repre- 

 sented in the peduncle, and tortuous capillaries are seen running up among the capsules. 

 B and o represent the termination of the nerve with the distal end of the central cavity 

 and adjoining capsults, to illustrate varieties of arrangement. In B the fibre, as well as 

 the core and adjoining capsules, is bifurcated. 



the peduncle, unless when the latter supports two corpuscles ; it retains its dark 

 double contour until it reaches the central cavity, where, diminished in size, and 

 freed from its perineurium, it becomes somewhat flattened, and presents the 

 appearance either of a pale, finely granular, and very faintly outlined band or 

 stripe, little narrower than the previous part of the fibre, or of a darker and more 

 sharply defined narrow line ; differing thus in appearance according as its flat side 

 or its edge is turned towards the eye. The pale aspect which the fibre presents in 

 the centre of the corpuscle has with some probability been ascribed to its losing the 

 white substance or medullary sheath on entering the cavity. Henle and Kolliker, 

 however, think that it is more likely the result merely of a diminution in size, 

 together with a certain degree of flattening. It sometimes happens that the fibre 

 regains its original magnitude and double contour for a short space, and changes 

 again before it terminates ; this is especially liable to occur while it passes through a 

 sharp flexure in a crooked central cavity. The fibre ends by a sort of knob at the 

 further extremity of the median cavity, which is often itself somewhat dilated. In 



