146 DR. E. KLEIN. 



place myself on the side of those (EwalJ, v. Ebner, Eanvier) 

 whose observations of this and similar glands, especially mucous 

 glands, has led them to the conclusion that '' mucous cells " 

 possess in the different phases of function a different aspect, that 

 they are not destroyed during secretion, but after secretion are 

 capable of returning again to the former state of rest. Such 

 is the conclusion to which a general consideration of secretory 

 action would, a priori, lead us, and the above observations fully 

 bear that out. They have shown us that mucous cells possess a 

 state of rest, in which they show an inner more longitudinally 

 fibrillated and an outer more reticulated part, containing in 

 its meshes the '' mucigen." Then there is another phase, that 

 of secretion, in which the cells are larger, and the "mucigen," 

 transformed into mucin ; after this the cells again return to 

 their former state, first, however, showing a more uniform 

 network of fibrils. The nuclei of the mucous cells are subjected 

 to only one change, viz. in the last phase they are less compressed, 

 approaching more or less the spherical shape. 



But although I do not admit that under normal conditions 

 of function Heidenhain's theory is applicable, I do not say 

 that such is not the case under certain abnormal conditions. 

 The observations of Ileidenhain, Boll and Lavdowsky leave no 

 doubt that if the gland is exhausted by a long-continued 

 stimulation, the alveoli assume a uniformity of structure, all 

 the cells appearing of the nature of the " granular " cells of the 

 crescents. Heidenhain explains this, as stated above, by saying 

 that all the mucous cells having heen destroyed the parietal cells 

 have to make up for them. Lavdowsky,^ on the other hand, 

 shows that this is partly due to the mucous cells changing into 

 small " granular " elements, and partly to a new formation of 

 such cells from those of the crescents. That the alveoli in a 

 young condition contain only "granular" cells, some of which 

 change into mucous cells, this I have mentioned above, and 

 from this experience I am not at all disinclined to accept the 

 explanation of these authors, if it can be shown that the mucous 

 cells are destroyed in great masses. As far as my experience 

 goes of glands in normal function, I have not seen any mucous 

 cells changing into cells that at all look like the parietal cells, 

 and for this reason I cannot accept the force of the argument of 

 Ewald, who by a process of " mucous abstraction " tries to render 

 the mucous cells similar in appearance to the parietal cells. Ewald^s 

 experiments do not seem to me to prove at all that Heidenhain's 

 explanation is not correct, for Ewald does not tell us that he ever 

 saw in any phase of the secretion the mucous cells actually turn 

 into " granular" cells similar to those of the crescents. 

 iL. c, p.329. 



