CHAP. I.] CHANGES IN GLAND CELLS DURING SECRETION. 15 



Structural Changes in Secretory Cells accompanying activity of the 



Salivary Glands. 



The researches made during the last few years by Heidenhain, 

 Ebstein and Griitzner, Langley, and fully confirmed by a large 

 number of observers, have demonstrated that in the salivary glands, 

 as perhaps in all secreting glands, structural and perfectly obvious 

 microscopic changes occur, which stand in close relation to the 

 different conditions of functional activity. 



The resting gland cell is large, but possesses compa- 

 of restin Cteri Datively little protoplasm, and therefore comparatively 

 glands. little matter which can be stained by colouring 



matters, especially by carmine ; it contains, instead, a 

 store of material which has been elaborated in, or at the expense of, 

 the protoplasm. This material does not constitute the specific 

 matter of the secretion, but is its antecedent. 



That a chemical difference exists which admits of direct proof is argued by 

 Heidenhain, in the case of the mucous glands for several reasons, but mainly 

 on the ground of the statements of Wabney and Klein, that whilst mucin is 

 stained by hsernatoxylin, its antecedent (mucigen) is not affected by that 

 colouring matter. Mr J. N. Langley, who has devoted much attention to 

 this question, has arrived at the conclusion that as yet no evidence what- 

 ever exists which warrants the assertion that such a hypothetical mucigen 

 exists. In a hitherto unpublished note on the subject which the author 

 has had the advantage of reading, he points out, inter alia, that hsema- 

 toxylin when added to saliva does not stain the mucin which that fluid 

 contains, unless it be in a solution which contains alum. 



The behaviour of the gland cells towards hsematoxylin varies greatly 

 according to the treatment which the tissue has undergone. Langley has 

 frequently obtained sections of gland hardened in alcohol with a stringy 

 mass of mucin in the ducts, and on staining with haamatoxylin (whether 

 Kleinenberg's, or Bohmer's or Delafield's, or in aqueous solution, or in 

 dilute alkaline solution), obtained good staining of nuclei and demilunes 

 without the mucin having taken a trace of colour. If we are to rely 

 on the hsematoxylin test we must, in such cases, conclude that the saliva 

 in the duct did not contain mucin but mucigen. ' It is possible,' says 

 Langley, 'that a method of staining with hsematoxylin may he found 

 which shall give satisfactory results; for sometimes the substance in the 

 duct is stained more than the cells and sometimes the cells are unequally 

 stained, but at present one cannot use hsematoxylin in such a way as to 

 give such results constantly.' But Langley's criticism is not limited to the 

 chemical grounds which have been alleged in favour of the hypothetical 

 mucigen. He considers that the physiological evidence in favour of its 

 existence is at present insufficient. The further discussion of this question 

 is beyond the scope of the present work. 



Characters- When, however, a gland passes into a state of 



tics of glands activity, as for example by the irritation of its so-called 



in a state of secretory nerves, the gland cells undergo the following 



activity. changes, which may proceed simultaneously, though 



