198 JOHN SUNDWALL 



2) Even the granules within one cell may be subdivided into 

 a number of groups, each group representing a specific chemical 

 structure and contributing some element to the sum total of 

 secretion. If such be the case one may readily assume a selec- 

 tive action on the part of each group for specific stains. Of course 

 we have no proof for such an assertion. 



3) A possible explanation lies in the fact that in the differen- 

 tiation of sections stained in either iron haematoxylin or copper 

 chrome haematoxylin some granules hold these stains much more 

 tenaciously than do others. This may be due to varying degrees 

 of fixation of the granules. It is the faintly stained granules, 

 those differentiated most, that are stained again in mucicarmin. 

 This observation had been made. 



However, as Bensley has pointed out: 



The difficulty of all these discussions of the different staininj;- prop- 

 erties of granules in the same cell arises from our ignorance of the 

 changes which would be produced in the absorptive properties of these 

 colloids with variations in their water content and so in their dispersion 

 grade. The dj^es which we use for this staining are all dyes which 

 may be absorbed. I think under the circumstances it would be rash 

 to assume a difference in the fundamental composition of the granules 

 on the basis of the different staining. 



Are the cells of the tubules and intercalary ducts of the same 

 functional type? Attention has been called to the fact that the 

 intercalary duct stains more deeply in the ordinary dyes than do 

 the tubules (v. Ebner, Nussbaum, and Langley, submaxillary 

 gland; Merkel and Fleischer, lachrymal gland). Fleischer con- 

 cludes that this duct has a specific secretion differing from that 

 of the tubules. He gives as his reason the presence of such 

 large granules. 



I too have observed that the intercalary duct as a rule stains 

 more deeply in the ordinary dyes. This can be readily explained 

 by the fact that the cells are smaller and more compact and 

 that the granules are conserved in such general fixatives as 

 Zenker's solution, while in the majority of cells of the tubules the 

 granules are not fixed but an intergranular cytoplasmic network 

 remains. 



