382 



On the Structure, of Serous Glands. 



[Nov. 27, 



show differences similar to those described above for the parotid under 

 similar circumstances. In early digestive stages, however, the grannies 

 appear sharper and more refractive, the distinctness of the cell net- 

 work depends largely on the alcohol treatment. 



I can confirm the observations of Bermann* on the presence of a 

 " tubular gland " in the sub-maxillary of the rabbit. The large lumen 

 and small cubical epithelium of the majority of the tubes do not 

 suggest that it has any important secretory function. 



The Infraorbital and Lachrymal Glands of the Babbit. 



In these glands the two zones in the secretory condition are even 

 more conspicuous than in the parotid-. Even more readily too than in 

 parotid can lobules thin enough for observation' be obtained. 



In different animals the alveoli may be granular throughout, or 

 may have a more or less distinct outer non-granular zone. But 

 whichever condition occurs the granules can always be diminished by 

 setting up a secretion with pilocarpus A similar change, I think, tooi 

 occurs on stimulation of the sympathetic. 



These glands are distinguished from the parotid and sub-maxillary 

 by preserving fairly their normal aspect after osmic acid and alcohol 

 treatment. The resting gland is not unlike, in chief features, the 

 resting parotid ; the network is particularly obvious. 



When a clear zone is present in the fresh state it stains easily with 

 osmic acid, showing ordinarily no network ; with a small non-granular 

 zone the granular zone appears as a network in the preserved specimen, 

 as the former increases the latter appears more granular and less as a 

 network. In activity the nuclei become spherical, move towards the 

 middle of the cells, and become less conspicuous. 



Recalling what has been said of the parotid and sub-maxillary 

 glands, it will be seen that in these, as well as in the infraorbital and 

 lachrymal glands, the alveolar cells in the secreting condition stain 

 much more homogeneously with osmic acid than they do in the 

 resting condition. In the two latter glands the homogeneous staining 

 corresponds in extent with the clear zone of the fresh specimen, in 

 the parotid this is to a slight extent only the case, in the sub- 

 maxillary gland scarcely at all. I am inclined to think that by a 

 modified use of osmic acid, the normal appearances in all these glands 

 may be more nearly preserved than is commonly the case, though, 

 undoubtedly, a great part of the divergence mentioned above in their 

 behaviour in the secretory state, depends on a chemical difference in 

 the substances broken down and re-formed. 



The investigations, of which the foregoing is a brief account, were 

 carried on in the Physiological Laboratory of the University of 

 Cambridge. 



* " Ueber die Zusammensetzung der Gfandula Submaxillaris." Wurzburg, 1878. 



