NERVE-ENDINGS. 309 



protoplasm curved fibrils, so situated that the convex sides are 

 always toward the centrally placed nucleus. Grandry's cor- 

 puscles are found especially on the cutis of the cere of the 

 bill of aquatic birds, such as the goose and duck. They occur 

 also in the tongue. The tactile cells of Grandry's corpuscles 

 are of connective-tissue origin, as shown by Szymonowicz. 

 Thus their origin is entirely different from that of MerkePs 

 tactile bodies. 



The other kinds of nerve-endings in connective tissue may 

 be grouped under what are known as end bulbs. In all termi- 

 nations of this sort we can distinguish three constituents, 

 namely, the axis cylinder, a thickened structure surrounding 

 this, and a capsule enclosing the whole. The axis cylinder 

 usually ends in a small swelling. The capsule is composed 

 of connective tissue, and contains a small number of connec- 

 tive-tissue cells. These end bulbs are usually long, and often 

 spirally coiled. In some cases the axis cylinder breaks up 

 into many branches, each of which terminates in a thickening, 

 and is surrounded by connective-tissue sheaths. End bulbs of 

 this sort are found in the skin of the pig's snout (Szymonowicz) 

 and in the conjunctiva (Krause). 



End bulbs of a more complex character are found in the 

 genitalia, especially in the glans penis and the clitoris. In 

 these so-called genital nerve corpuscles the axis cylinder breaks 

 up into many branches which, according to some authors 

 (Retzius), end freely, and according to others (Dogiel), form 

 a dense network. 



The so-called Meissner's tactile corpuscles (Fig. 244), which 

 occur especially in the papillae of the skin, may be considered 

 as end bulbs. They are ellipsoidal corpuscles, often more than 

 100 u long and 50 LL wide. They are surrounded by a thin 

 nucleated connective-tissue capsule which contains a gelatinous 

 inner sheath. At the lower pole of the corpuscle, one to four 

 nerve fibres are usually present. They lose their medullary 

 sheath immediately after entering the connective-tissue capsule. 

 The naked axis cylinder takes a spiral course and breaks up 

 into many branches in the inner sheath. There can usually 



