MORPHOLOGICAL CONSTITUENTS OF THE SALIVA. 453 



various sizes. I have named this mode of nerve termination, 

 that by a " protoplasmic foot." If, as I have sometimes ob- 

 served, many of the nuclei appear to be provided with fibres, 

 which can be followed into the interior of the nerve fibres, it is 

 highly suggestive of the development of the gland cells from 

 the nerves. 



In regard to every explanation it must be observed that 

 transitional forms may occur, respecting which it is impossible 

 to say whether they are epithelial or nervous. The continuous 

 and luxuriant neoplastic formation taking place in the sub- 

 stance of the salivary ducts presupposes their regeneration, 

 respecting which I have formed my own opinion, but have 

 arrived at no definite conclusion. In like manner the per- 

 sistent neoplastic formation of the alveoli in adult animals 

 determines an atrophic detachment of those already present. 

 In Moles I have sometimes found the alveoli with pale offshoots 

 of various forms, and pale finely granular contents, which may 

 be such atrophied and separated alveolar segments. 



I first comprehended the complexity of all forms of salivary 

 glands when I recognised the constant production and disinte- 

 gration taking place in them, which is referrible to the nerve 

 substance. 



6. THE MORPHOLOGICAL CONSTITUENTS OF THE SALIVA. 

 Healthy saliva contains no morphological elements, but forms 

 a transparent perfectly homogeneous fluid. But when the 

 mucous membrane is irritated, either by ligature of the excre- 

 tory duct, or by the introduction of a canula into its interior, 

 we obtain isolated morphological elements, which are conti- 

 nuously developed by a kind of catarrhal condition and exuda- 

 tion. The appearance of these has led some observers to the 

 belief that normal saliva contains formed elements, and con- 

 tinually carries off glandular epithelium. As recent investi- 

 gations have been in direct contradiction to these statements, I 

 may perhaps be allowed briefly to state the grounds on which 

 my opinions are based. When, in a dog, the duct of Wharton 

 and the nerves supplying the submaxillary gland have been 

 exposed, isolated, and divided, a watery saliva flows from the 

 duct, as transparent as a dewdrop. The secretion found in the 



