THE SENSE OF TOUCH. 587 



which serve as intermediates between the stimulus, on the one hand, 

 and the afferent nerves, on the other hand. By virtue of their struc- 

 ture they are far more irritable than the nerve-fibers and hence 

 respond more quickly to the physiologic stimulus than the nerve- 

 fiber itself. To these specialized organs, found not only in the 

 skin but in other sense-organs as well, the term peripheral or terminal 

 organ is given. It is these structures that are primarily excited to 

 activity by the physiologic stimulus, and that in turn arouse the 

 nerve to activity. Peripheral organs are to be regarded as special 

 modes of termination of afferent nerves and adapted for the impress 

 of a specific stimulus. The peripheral organs of afferent nerves 

 found in the skin and oral mucous membrane present a variety of 

 forms, some of which are as follows: 



1. Free Endings. These are pointed or club-shaped processes, the 



ultimate terminations of af- 

 erent nerve-fibrils, found in 

 and among epidermic cells. 



2. Tactile Cells. These are oval 



nucleated bodies found in 

 the deeper layers of the 

 epidermis. They rest upon 

 or are embraced by a cres- 

 centic shaped body, the 

 tactile meniscus, which in 

 turn is directly connected 

 with the nerve-fibril and 



probablv a modification of it 



^ T7 . FIG. 270. TACTILE CELLS FROM SNOUT 



ing. 270). OF PIG. a. Tactile cell. m. Tactile 



3. The Corpuscles of Meissner disc. n. Nerve-fiber. (Stirling.) 



and Wagner. In the papillae 



of the derma, especially in the palm of the hand and in the 

 finger-tips, are found elliptical bodies consisting of a connective- 

 tissue capsule containing a number of tactile discs with which the 

 nerve-fibrils are connected. If the afferent nerve is traced to 

 the capsule, it is found to lose both its neurilemma and medulla, 

 after which the naked fibril penetrates the capsule, breaks up 

 into a number of branches, and after pursuing a more or less 

 spiral course becomes connected with the tactile discs (Fig. 271). 



4. Hair Wreaths. Just below the openings of the sebaceous gland 



the hair follicles are surrounded by naked axis-cylinder fibrils 

 in the form of a wreath, which in all probability terminate in 

 the cells of the external root-sheath. These, too, are to be 

 regarded as part of the touch apparatus. 



5. Corpuscles of Vater or P acini. These are oval-shaped structures 



found along the nerves distributed to the palms of the hands and 



