274 



MUCOUS AND SEROUS GLANDS. 



[BOOK ii. 



In the case of the serous glands also the results are somewhat 

 different according as use is made of preparations hardened in 

 alcohol, or the gland is studied in a living state. Thus in the 

 parotid of the rabbit, which is a serous gland, even when a most 

 copious secretion has been called forth by stimulation of the auriculo- 

 temporal nerve, alcohol specimens shew an almost complete absence 

 of structural changes. When however the cervical sympathetic is 

 stimulated, either in the rabbit or the dog, very marked changes, 

 quite similar to those witnessed in the central cells of the gastric 

 glands, may be 'seen in the parotid hardened by alcohol, even though, 

 as occurs in the dog, no saliva whatever may be secreted. During 

 rest the cells of the parotid as seen in sections of the gland 

 hardened in alcohol (Fig. 53 A) are pale, transparent, staining with 

 difficulty, and the nuclei possess irregular outlines as if shrunken 

 by the reagents employed. After stimulation of the sympathetic, 

 the protoplasm of the cells becomes turbid (Fig. 53 B), and stains 

 much more readily, while the nuclei are no longer irregular in 

 outline but round and large, with conspicuous nucleoli, the whole 

 cell at the same time, at least after prolonged stimulation, becoming 



A 



FIG. 53. SECTION OF A 'SEROUS' GLAND: THE PAROTID OF THE RABBIT. A at 

 rest, B after stimulation of the cervical sympathetic. (After Heidenhain.) 



distinctly smaller. When however we study the gland in a living 

 state, we find that the changes which take place during activity are 

 quite comparable to those of the pancreas. During rest (Fig. 54 A), 

 the cells are large, their outlines very indistinct, in fact almost 

 invisible and the protoplasm of the cell is studded with granules. 



FIG. 51. ^ CHANGES IN THE PAROTID DURING SECRETION (Langley). 

 The figure which is somewhat diagrammatic represents the microscopic changes 

 which may be observed in the living gland. A. During rest. The obscure outlines 

 of the cells are introduced to shew the relative size of the cells, they could not be 

 readily seen in the specimen itself. B. After moderate stimulation. C. After 

 prolonged stimulation. The nuclei are diagrammatic, and introduced to shew their 

 appearance and position. 



