THE PERIPHERAL NERVE-ENDINGS. 



93 



FIG. 114. 



between the acini. The nerve-fibrillae may be traced readily to the 

 membrana propria of the acini, around which a net-work is spun ; 

 regarding their ultimate distribution and relation to the secreting 

 cells much uncertainty still exists, notwithstanding many elaborate 

 investigations and positive statements. 



The exact mode in which the nerves terminate within the acini is 

 still doubtful ; it is probable, however, that the fibrillae end between, 

 or in apposition with, the ends of the secreting cells directed towards 

 the basement-membrane ; proof of direct con- 

 nection between the nerve-fibrillae and the se- 

 creting cells is, at present at least, wanting. 

 Likewise, the mode of termination of the med- 

 ullated fibres, which, as already stated, con- 

 tribute to form the interlobular net-work, is 

 uncertain ; in some glands, as in the pancreas 

 of the cat and the buccal glands of the hedge- 

 hog, they terminate in special nerve-endings 

 resembling the corpuscles of Vater. 



The perceptive apparatus connected with the 

 termination of the nerves of special sense 

 include the highly specialized epithelial struct- 

 ures made up of the neuro-epithelium ; the 

 rod- and cone-cells of the retina, the hair-cells 

 of the internal ear, the olfactory cells of the nasal fossae, and the gus- 

 tatory cells of the taste-buds are important examples of such tissue. 

 In these structures the specialized epithelium forms the apparatus for 

 the reception of the external stimuli, while the nerve-fibres provide 

 for the further transmission of the impressions so appreciated. The 

 relation between the receptive cells and the conducting nerve-fibres 

 must be, evidently, very intimate ; a direct anatomical continuity 

 between the two, however, though probable, must be regarded as 

 still lacking positive demonstration. 



Nerves ending in glands, 

 from the parotid of dog ; 

 gold preparation : s, group 

 of secreting cells of single 

 acinus ; , nerve-fibre lying 

 outside the membrana pro- 

 pria and giving off twigs 

 which enclose the acinus 

 within a net-work of ter- 

 minal nerve-fibrillae. 



