398 INNERVATION. [CHAP. XIII. 



element of the areolar tissue. The internal capsules do not shew 

 the double wall, but they contain nuclei. 



The capsules seem to be over- distended by their fluid, so as to be 

 naturally kept tense. If allowed to dry, they do not fill again on 

 being moistened. 



The fluid of the intercapsular spaces is so abundant as to constitute 

 far the largest portion of the bulk of the entire corpuscle, and by its 

 clearness imparts the peculiar pellucid lustre so characteristic of 

 these bodies. It is supposed to resemble the serum of the blood. 



There are generally a few capillary blood-vessels ranging over the 

 surface of the corpuscles ; but the capsules are chiefly supplied by a 

 minute artery that enters in the fibrous tissue of the stalk, sends off 

 a few capillaries which perforate the tubular canal, and form each a 

 short loop in the intercapsular space (fig. 75): one capillary vessel 

 usually reaches the central capsule (fig. 76, A), and sometimes, though 

 rarely, may be traced some way along its wall. In the larger cor- 

 puscles of the palm and sole, the capillaries penetrate to the distal 

 part of some of the intercapsular spaces, and may there form a kind 

 of bunch before returning. If a quite recent specimen be examined, 

 under a high magnifying power, the blood-globules are often visible 

 in the capillaries, and, by their swelling on the addition of water, 

 may be sometimes hurried into a sort of circulation. When this 

 happens, the course of the blood in the corpuscle is displayed with 

 singular beauty. 



We have said that the stalk of every corpuscle contains a single 

 nerve-tube. When two corpuscles are seated on a common stalk, two 

 nerve-tubes are included, one of which belongs to each (fig. 74, c). 



The nerve-tube is proportioned in size to that of the corpuscle, 

 that is, to the number of capsules composing it. Even when 

 smallest, it is conspicuous enough, if the specimen be recent ; for 

 it is invariably furnished with the white substance of Schwann, and 

 displays the double contour. When largest, it equals any found in 

 the body. It is very liable to present varicosities, and its course in 

 the stalk is more or less undulating. 



On entering the innermost capsule, the nerve-tube suddenly loses 

 its envelope of white substance and becomes pale ; the axis-cylinder 

 alone remaining, perhaps still invested by the tubular membrane 

 (see p. 208). Thus reduced in size and rendered pale, the nerve 

 stretches like an arrow along the very centre of the capsular cavity 

 to the opposite end, where it swells into a knob, or button, which 

 fixes itself to the inner surface of the capsule. In this swelling 

 nothing can be detected beyond the pale, faintly fibrous cha- 



