chap, xv.] PERIPHERAL NERVE-ENDINGS. 121 



(touch-cells of Merkel) ; according to others (Key and 

 Retzius, Ranvier, Hesse, Izquierdo), in the trans- 

 parent substance between the touch-cells, thus form- 

 ing the * disc tactil ' of R,anvier or the Tastplatte of 

 Hesse. Neither theory seems to me to answer to the 

 facts of the case, since I find that the branchlets of 

 the axis cylinder terminate, not in the touch-cells, nor 

 as the disc tactil, but with minute swellings in the 

 interstitial substance between the touch-cells, in a 

 manner very similar to what is the case in the con- 

 junctival end bulbs. According to Merkel, single or 

 small groups of touch-cells occur in the tissue of the 

 papillae, and also in the epithelium, in the skin of 

 man and mammals. 



157. In articulations e.g., the knee-joint of the 

 rabbit Nicoladoni described numerous nerve branches, 

 from which fine nerve-fibres are given off. Some of 

 these terminate in a network, others on blood-vessels, 

 and a third group enter Pacinian corpuscles. Krause 

 described in the sy no vial membranes of the joints of 

 the human fingers medullated nerve-fibres which end 

 in peculiar tactile corpuscles, called by him " articula- 

 tion-nerve corpuscles." 



158. The nerve branches supplying non- 

 striped muscular tissue are derived from the 

 sympathetic system. They are composed of non- 

 medullated fibres, and the branches are invested in 

 an endothelial sheath, perineurium. The branches 

 divide into single or small groups of axis cylinders, 

 which reunite into a plexus the ground plexus of 

 Arnold. Small fibres coming off from the plexus 

 supply the individual bundles of non-striped muscle 

 cells, and they form a plexus called the intermediary 

 plexus (Fig. 76). The fibres joining this plexus are 

 smaller or larger bundles of primitive fibrillae ; in 

 the nodes i.e., the points, of meeting of these fibres 

 are found angular nuclei. From the intermediary 



