18 S. B. VINCENT 



The embryological studies of Szymonowicz ('95) prove that 

 these cells originally lay in a horizontal layer between the cutis 

 and the epidermis but were pushed by the formation of the cutis 

 papilla into the inter-papillary spaces and finally lay in groups 

 over each other. Botezat ('97, p. 103) tells how in the invagi- 

 nation of the hair follicles these cells and the nerve endings are 

 carried down and lie in the root sheath of the follicle in the same 

 position which they originally occupied on the cutis border. He 

 calls attention to the fact that if one were to fix a hair in one of 

 these groups of cells, particularly in Elmer's organ, one would 

 have a structure very similar to the hair follicle without the 

 fibrous sheath. He mentions the likeness of the touch cells to 

 the cells of Grandry's corpuscles and also to the platelets which 

 Bethe describes in the tongue of the frog. Merkel found the 

 touch cells in the region of the mouth or nasal openings of many 

 mammals and apart from this part of the body chiefly in the 

 unhaired portion of the skin. He also found them on the hard 

 palate and the bills of birds, on the tail of the hedgehog and 

 the vuh'a of swine. In man he said they are situated for the 

 most part where there are no Meissner's corpuscles. There are 

 many over the abdomen. Ran^'ier ('60) says there are more 

 menisques in the finger tips than there are cells. 



Enough has been said I think to show the very general distri- 

 bution of these simple endings; of the functional importance as 

 well as the particular distribution we will speak later. 



The nerve ring may be explained as the position of the touch 

 cells has been explained, as arising as a result of the process of 

 invagination. In the infolding of the follicular layers the nerve 

 plexus is carried down too for a short distance. The follicle 

 finally l^reaks through it but in the subsequent enlargement of 

 this organ, and great increase in diameter, the fibers of the plexus 

 are stretched out in the so-called ring. The brush-like ends which 

 are seen cut across in the conical body are a part of this same 

 plexus and from these fibers may often be seen running up to 

 the surface. These nerves in the hair then have Tie special 

 function but are simply a distorted part of the common skin 

 plexus. 



