TACTILE TISSUES 



203 



ending, found in the connective tissue lying between the muscles 

 of the cat, is used apparently to record the pressures produced by 

 the movements of the body. Each of them, known as a cylin- 

 drical corpuscle, consists of a very plain, al- 

 most straight and somew r hat granular, single 

 nerve termination, the end of a nerve fiber to- 

 gether with other tissues placed around it. Its 

 extreme end is irregularly bent. The granular 

 material in which it lies is called the inner bulb 

 and is probably a product of the capsule cells. 

 The connective-tissue coverings are only four or 

 five in number, with nuclei occurring at fre- 

 quent intervals between the layers. These con- 

 nective-tissue cells form plate-like areas of the 

 connective-tissue substance and the plates are 

 joined into a series of coverings. Consequently, 

 the appearance of the coverings is the same in 

 any section that cuts the central axis, a series 

 of thread-like rings of tissue with the nuclei 

 scattered between them. The coverings are con- 

 tinuous with the sheath of the nerve (Fig. 182). 



Various modifications of this simple form are 

 found, with more or less coverings and with vari- 

 ations in the shape of the nerve-ending, which, 

 however, is primarily a single, approximately straight rod. Its modi- 

 fications consist of granulations and fine side processes. Sometimes 

 a second small fiber enters the capsule and forms a plexus around the 

 main termination. 



The second specimen of a simple encapsulated nerve end-organ, whose 

 intermediate structures operate on the hydraulic pressure plan, is found 



in the skin and other parts of the periphery 

 of mammals. The differences which it and 

 the rest of its class exhibit, when compared 

 with those just mentioned, are a branching 

 and anastomosing end-organ whose fibrils 

 are irregular in course and in shape, but 

 whose contour is smooth instead of granular, 

 Methyiene blue' picture. (After as was the case in the preceding form. 

 DOGIEL in Arch.f. mik. Anat.) There ^ ^^ & somewna t thinner capsule, 



which probably permits other sorts of motions and pressures to be 

 transmitted than the purely hydraulic kind. 



A type of this form is shown in the end-bulb of Krause from the 

 conjunctiva of man (Fig. 183). The various other forms of this group, 



FIG. 182. Nerve-endings 

 (tactile) in intermuscular 

 septum of cat, showing the 

 outer capsule and the in- 

 ner granular cytoplasm 

 which contains the rod- 

 like nerve-ending. (From 

 BOHM and DAVIDOFF'S 

 " Histology " by HUBER.) 



FIG. 18^ 



