142 DB,. E. KLEIN. 



portions of lobules in which the crevccuts are conspicuously 

 better developed than in other parts, and on careful comparison 

 it will be found that also the central or mucous cells of 

 these parts appear larger and better stained in hfematoxylin. 

 The contents of the mucous cells are here of a more or less 

 distinctly purple-blue tint, whereas in the other lobules, the 

 mucous cells are not stained at all or only slightly so. AYe know 

 from the observations of Dr. Watney^ that in ordinary mucous 

 glands, e. g. in the tongue, we can, with the aid of hsematoxylin 

 staining, easily ascertain which gland or parts of gland are 

 just in the act of mucous secretion and which not, for where the 

 cells are charged with mucin they stain in a characteristic 

 purple-blue tint. The thicker the layer the more pronounced 

 the colour. Dr. Watney showed me this very chaBacteristic re- 

 action also in the test-tube ; even the smallest quantity of mucous 

 — no matter what its reaction, whether alkaline or acid — becomes 

 precipitated by the addition of a drop of hsematoxylin solution 

 — the usual watery solution of extract of logwood — as flakes of 

 deep purple-blue to blue colour. 



Hence it becomes clear that also in the submaxillary gland 

 the blue staining of the mucous cells is due to the presence of 

 mucin in them. 



I am quite aware that, as Heidenhain, Pfliiger and v. Ebner have poioted 

 out, there is iu the submaxillary as well as in other mucous glauds a post- 

 mortem change of the " mueigen " into mucin, but this takes place only 

 if the gland be not placed early enough into the hardening spirit. In the 

 above description I was referring only to those cases where immediately 

 after the animal had been killed by bleeding, small bits of the organs had 

 been placed into the spirit. Besides, those glands that have suffered that 

 post-mortem change do not show well the outlines of the cells (v. Ebner), 

 as I can fully confirm. In my case I have another more weighty reason for 

 assuming the presence of mucin in the mucous cells already iu the living, it 

 is the fact that in those lobules the ducts contain mucin stained iu the 

 purple-blue tint. 



From these facts, viz. that there are present lobules or parts 

 of lobules in which the " crescents'' are enlarged and the mucous 

 cells are charged with mucin, not "mueigen," as in the rest- 

 ing state, and that also the corresponding duct contains mucin, 

 I infer that in the so-called resting state of the gland, but pro- 

 vided the animal be kept without food for some time, there are 

 parts in which the formation of mucin out of mueigen is 

 already going on. I shall have to mention further below a 

 similar relation in the mucous glands of tongue and oesophagus 

 of the same animal. 



Lavdowsky also states- that in the resting glands there may 



^ 'Proceedings of the Royal Society,' vol. xxii, p. 293, and 'Philosoph. 

 Transactions,' 1876, ii, p. 772. 

 - L.c, p. 318. 



