THE LACHRYMAL GLAND 181 



salivary ducts and that they remind one of the nebenkerne in the 

 pancreatic cells of the amphibians as described by Macallum, 

 Erberth, and Miiller. In a later contribution ('08) he suggests 

 the probabihty of serous cells being made up of various groups. 

 By using the following technique (1) examination of fresh mate- 

 rial in blood serum, teased preparations or sections cut with 

 Valentine knife, (2) experimental fixation, by which a fixative 

 medium was obtained which would preserve the secretion ante- 

 cedents in a form which is present in living cell, (3) differential 

 microchemical staining, Bensley has obtained results ''which 

 seem to justify the subdivision of the serous class of cells into a 

 number of subordinate groups" such as (1) 'tropochrome cells' 

 which stain metachromatically under certain fixations and stains, 

 and (2) 'homochrome cells' which do not stain metachromatically 

 and in all liklihood form a heterogeneous group. In a still later 

 contribution ('11) he speaks of prozymogen granules ''zymogen 

 granules in process of formation. . . . These must not be 

 confused with the basophile substance of the cell which has 

 elsewhere been called 'prozymogen' by Macallum and myself." 

 These prozymogen granules stain deeply in neutral red when used 

 as a vital stain. 



Mucous cells 



Regarding the main differences between mucous and serous 

 cells as revealed by more perfect fixations and staining processes, 

 Bensley's ('03) conclusions may well be inserted here. The 

 following reasons are given for his conclusion that the cells of 

 the glands of Brunner, in eighteen out of nineteen genera exam- 

 ined, are of the pure mucous type — (1) granules (droplets?) 

 have a low refractile index which corresponds closely to the 

 mounting media; (2) no basal filaments, 'prozymogen,' in fixed 

 preparations (the microchemical test for organic iron shows 

 only relatively small amount of cytoplasmic nucleoproteid) ; 

 (3) the granules do not stain in iron haematoxylin or neutral 

 gentian; (4) mucous cell stain in mucicarmin and muchaematein; 

 (5) granules are soluble in weak alkaline solutions, insoluble 

 in 5 per cent solution of hydrochloric acid and in artificial gastric 



