70 



J.N. Langley, 



mucous salivary glands and the similar glands of the mucous mem- 

 brane of the mouth, nose, pharynx, oesophagus, etc. , a few exceptions 

 with the chief cells of mammalian gastric glands; the gastric glands 

 of such birds, fishes, reptiles and amphibia as I have examined; the 

 oesophageal glands of the frog; the pancreas; the liver. 



It will he seen that this list includes most of the secretory glands 

 of vertebrates. The mammary glands and sweat glands of mammals, 

 I have not yet sufficiently investigated to be certain whether they 

 have the same structure as the preceding. The intestinal glands and 

 the kidney, I omit for the present, since they have some special points 

 of structure depending upon their special function of absorption and 

 excretion respectively. 



The border- cells (Belegzellen) of mammalian gastric glands; the 

 pyloric gland- cells, and those of the chief cells which are not di- 

 stinctly granular in life — the exceptions mentioned above — I shall 

 consider separately. 



The secretory cells of all the glands in the list which I have 

 given, have the following common points of structure 2 ). 



The cell substance is composed of (a) a framework of living sub- 

 stance or protoplasm, connected at the periphery with a thin conti- 

 nuous layer of modified protoplasm ; the framework in some cases has 

 the form of a network of small threads of equal size as described by 

 Klein 2 ) ; in others of flattened bands. Further the threads or bands 

 may vary in size in different parts of the cell, and the meshes in 

 different parts of the cell may be of different size and shape. Within 

 the meshes of the framework are enclosed two chemical substances 

 at least, viz. (b) a hyaline substance in contact with the framework, 

 and of (c) spherical granules which are embedded in the hyaline 

 substance. 



In the gland -cells which secrete much organic matter the cell- 

 granules are conspicuous and fairly large. In the gland- cells which 

 secrete comparatively little organic matter, the cell -granules are ge- 



>) This I have already described for the liver- cells (Proc. Roy. Soc. No. 220, 

 Apr. 1882). 



2 ) Quart. Journ. Micr. Science, Apr. 1879. 



