II 



EXTERNAL DIGESTIVE SECRETIONS 



fine discovery, which enables us, up to a certain point, to penetrate 

 to the interior of the cells, and to ascertain what cytological 

 phenomena accompany the process of secretion. 



B 



FIG. 21. Rabbit's parotid. Alcohol-carmine method. (Heidenhain.) A, resting state ; 

 B, after stimulation of cervical sympathetic. 



Microscopic preparations "of serous glands hardened in alcohol 

 and stained with carmine show in the resting state a colourless 



O ? 







Fn;. 22. Orbital gland of dog. Alcohol-carmine method. (Lavdowsky.) A, resting statr : 

 B. maximal degree of change which the gland is capable of exhibiting in secretory activity. 



clear, finely granular cytoplasm, and a nucleus that stains red, 

 with wavy outlines and no distinct nucleoli (Fig. 21, A). After 

 excitation of the secretory nerve, and when some cubic centimetres 

 of saliva have been given off, the cells visibly alter in character. 



