CHAP, vi.] > SOME OTHER SENSATIONS. 1409 



oval form, 60 to 100 /JL in the long diameter, which, in certain 

 situations, are found in the papillse of the dermis lying im- 

 mediately beneath the epidermis. It is easy to recognize that 

 each touch corpuscle contains a number of oval nuclei placed 

 transversely, and that between the nuclei run irregular, but on 

 the whole transverse lines, having the appearance of transverse 

 fibres or septa, the whole being surrounded by an indistinct 

 capsule. This arrangement gives the whole body an appearance 

 not unlike that of a miniature fir cone. A medullated nerve 

 fibre, generally with a more or less coiled course, reaches the 

 corpuscle, most commonly at the side, and after twisting round 

 the body to a variable extent, and frequently dividing, is finally 

 lost to view in the midst of the corpuscle. Sometimes the cor- 

 puscles appear compound, as if made up of more corpuscles than 

 one joined together, the whole body appearing lobed. 



It is easy to recognize this much ; but the further details of 

 the structure of a touch corpuscle are matters of great difficulty, 

 about which much divergence of opinion obtains. Perhaps the 

 view which at present most commends itself is to regard them as 

 formed on the same plan as a compound corpuscle of Grandry, but 

 with the constituent elements less distinct. According to this 

 view the transverse nuclei are the nuclei of subsidiary cells, in con- 

 nection with which the divisions of the axis cylinder of the nerve 

 fibre end in expansions comparable to the terminal plates of the 

 corpuscle of Grandry, the characteristic transverse strise being the 

 expression of the divisions of the nerve fibre. But in the touch 

 corpuscle the subsidiary cells are not so well formed as in the 

 corpuscle of Grandry, and moreover seem especially placed towards 

 the surface of the corpuscle, leaving the interior free at least from 

 nuclei ; the division of the nerve fibre is also more complete, the 

 fibre often breaking up into clusters or bunches of branches ; the 

 medulla accompanies the dividing axis cylinder for a greater 

 distance into the interior of the body ; and the conspicuous 

 terminal plates of the corpuscle of Grandry are replaced by mere 

 slightly swollen knobs. Without insisting too much on the value 

 of the analogy, we may probably conclude that in the touch 

 corpuscle we have to do with an axis cylinder, which dividing 

 frequently, ends abruptly in contact with, or in connection with, 

 but not in continuity with certain cells of a peculiar nature. 



Touch corpuscles are found in man most abundantly on the 

 palmar surface of the hand, especially of the fingers. It has 

 been calculated that the palmar surface of the tip of the fore- 

 finger contains about 100 touch corpuscles for each two square 

 millimeters, that of the second joint 40, and that of the third joint 

 15 in a like area. They are also found, though somewhat less 

 plentifully, on the sole of the foot and toes, about 30 being present 

 in two square millimeters of the last joint of the great toe, and 

 seven or eight in the like area of the middle of the sole. They 



