76 THE SENSE OF TOUCH IN ANIMALS 



surface of the hand and plantar surface of the foot, and are here 

 arranged in Hues forming the curvihnear papillary ridges seen 

 on the surface of the epidermis. They are conical and may be 

 either single or compound and measure from -^^jj to yl^^ inch in 

 height. Whereas on the face they are reduced to -g-l^j or g^^j 

 inch ; and in other parts with a less developed sense of touch 

 than the hand and foot, the papillae are broader, lower and 

 fewer in number and irregularly scattered (Quain). 



In the hand and foot the papillae of the corium appear to 

 possess two separate functions, some of them being vascular 

 papillae containing networks of fine vessels and others are set 

 apart for the very important function of assisting the sense 

 of touch, and these contain the bodies known as touch-corpuscles 

 or Meissner's corpuscles, and, as a rule, no blood-vessels. These 

 corpuscles are small, oblong bodies about ^|^^inch long and ^^^ 

 inch broad and are composed of connective tissue with a capsule 

 surrounding them, and each contains the non-medullated nerve - 

 fibrils of a medullated nerve, and within the corpuscle the axis- 

 cylinders ramify. Nerve-fibrils of the non-medullated kind 

 also ramify among the cells of the epidermis. Hairs are entirely 

 absent from the palmar and plantar surfaces, and it is probable 

 that in other parts of the skin, where hairs exist, the rich net- 

 work of nerve-fibrils found at the roots of the hairs have a tactile 

 function, lower in degree than the highly developed papillae of 

 the corium found in the hand and foot. 



The ducts of the sudoriparous glands are evident in many of 

 the sections, and their openings which pass through the dark- 

 coloured rete mucosum are situated between the papillae of 

 the corium, the glands he in the areolar tissue and their ducts 

 pass through the corium in a straight line, becoming spiral in 

 their passage through the epidermis, open on the free surface. 

 Their orifices are seen on the surfaces of the ridges of the palmar 

 and plantar surfaces, being absent from the furrows between 

 the ridges. The under-surface of the epidermis, which presents 

 this row of projecting openings of sudoriparous ducts, is called 

 Driisenleisten by Schlaginhaufen and Miss Whipple. 



A diagram of a section of the human skin is here given (Fig. 52a) 



