328 MANUAL OF HISTOLOGY. 



185. 



Another modification, to a certain extent, of these end bulbs of Krause 

 is presented to us in the tactile or touch corpuscles of the skin (fig. 315). 



The nervous network supplying the latter give off primitive fibres 

 towards the bases of the so-called tactile papillae (p. 234), which pass 



Fig. 315. Vertical section of three groups of tactile papillae of the human index finger, 

 occupied partly by vascular loops, and partly by tactile corpuscles. 



forward either isolated or lying together in small fasciculi of microscopic 

 fineness. Here division of the nervous tubes, at acute angles, occurs 

 with great frequency. 



These touch-corpuscles may be found on the volar aspect of the fingers 

 and toes, and on the palm of the hand and sole of the foot. Their number 

 is greatest on the aspect of flexion of the last joints of the fingers, and 

 decreases then from the second to the first. In the palm of the hand 

 they are still fewer in number. Thus in the Q'" to 400 papillae, 108 

 tactile corpuscles were found by Meissner on the last joint of the finger, 

 while in the second joint the latter only amounted to 40, on the first to 

 15, and in the palm of the hand to 8. Their amount is also most con- 

 siderable on the last joint of the toes. Here, however, the proportion, as 

 compared to the hand, is very small. On the back of the hand, the 

 dorsum of the foot, and volar surface of the forearm, we may also en- 

 counter a few of these tactile corpuscles. Krause has found them, 

 besides, in the conjunctiva. Finally, they are to be met with in the 

 nipple and skin of the lips, though in but moderate number. In the 

 latter regions intermediate forms between them and the terminal bulbs 

 have been described. Among the mammals they have only been recog- 

 nised in the ape, in the palm of the hand, sole of the foot, and skin of the 

 lips (Meissner, Krause}. 



Size and form are liable to considerable variation. In the vola manus 

 they measure upwards of 0-1115 mm. with a breadth of 0-0451-0-0563 

 mm. Smaller specimens may only reach 0-0451-0-0377 mm. Those of 

 greater dimensions are usually oval ; those of smaller, mostly of rounder 

 figure. 



These structures are situated in the axis and apex of the tactile papillae, 

 but excentrically in those which are in any degree complex. Only the 

 latter are exceptionally supplied also with vascular loops (fig. 315 ; in the 

 middle a double papilla). Otherwise those which contain tactile cor- 

 puscles are non-vascular. 



The touch corpuscle consists of a capsule formed of a homogeneous 

 substance enclosing a finely granular soft matter best seen in transverse 

 section. 



In the capsule, further we may remark numerous elongated bodies 

 arranged transversely or obliquely. We shall refer to these again pre- 



