28 Mr Langley, On the Secretory Cells and on the [Nov. 12, 



apparently embedded in a homogeneous mass, which other reagents 

 show to be composed of network and hyaline substance. 



The same cells, after treatment with alcohol, show an indistinct 

 network, containing an interfibrillar mass in which the granules 

 and the hyaline substance cannot be separately seen. 



The oesophageal glands of the frog and the pancreas of all 

 animals, after treatment with alcohol, show the shrunken remains 

 of the granules, but leave the network and hyaline substance in- 

 distinguishable or nearly so. 



Even chromic acid which in most gland-cells brings out the 

 network clearly, does not act in quite the same manner on all 

 gland- cells, for it differentiates the network and hyaline substance 

 less clearly in the oesophageal glands of the frog, than in the 

 salivary and gastric cells; and differentiates them less clearly in the 

 pancreas than in the oesophageal glands of the frog. 



It will be noticed that the cells mentioned above form a series 

 in which the network and hyaline substance are less and less easily 

 distinguished from one another, that is, a series in which the net- 

 work and hyaline substance become more and more alike in 

 chemical characters. 



In the above general description I have not included the pyloric 

 gland-cells, the border cells (Belegzellen) of mammalian gastric 

 glands, or the semi-transparent chief-cells which are found in the 

 latter part of the greater curvature in some animals. In these 

 the changes described above as taking place in digestion have 

 not yet been observed. This, I think, is due to their containing 

 very small granules, which are not obvious during life, and which 

 are not preserved by any reagent ; in consequence a change in 

 their granularity is very difficult to observe. 



With regard to their structure they certainly have a frame- 

 work enclosing hyaline substance, the only difficulty is to show 

 that they contain also granules embedded in the hyaline substance. 



These cells in life do not show distinct granules, but when 

 they are teased out in salt solution they become very finely 

 granular. This is not caused by the cell network, for the network 

 has rather large meshes. In those chief-cells which are apparently 

 homogeneous in life, the granules are often fairly distinct on teas- 

 ing out the cells in salt solution; in the pyloric gland-cells the 

 granules are usually so indistinct that I should not feel justified 

 on the microscopic appearances alone, in assuming that they are not 

 due to a slight alteration in the hyaline interfibrillar substance. 

 There are however other grounds which render, I think, this 

 assumption justifiable. 



In all cells which contain much pepsinogen, distinct granules 

 are present. Further, the quantity of pepsinogen varies directly 

 with the mass (number and size) of the granules ; that is, pepsi- 



