504 



points to the correctness of the conclusion that the transparent cells 

 of the glands of Brunner are mucous cells. 



The darkly staining cells of the glands of Brunner of the rabbit, 

 are specifically different and independent of the clear mucous cells 

 from which they may easily be distinguished even in the fresh material. 



In the fresh tubules examined in serum or in aqueous humor, 

 these tubules are, as Schwalbe (72) has pointed out, easily dis- 

 tinguished from the mucous tubules by the fact that the apical zone 

 of the cells next to the lumen is filled with minute guanules of 

 zymogen. The appearance of such a fresh preparation is shown in 

 Fig. 2. The resemblance to a pancreatic acinus or to a partially 

 discharged acinus of a serous gland is striking. 



Fig. 2. Serous acinus from the glands of Brunnek of the rabbit; examined fresh 

 in aqueous humor. In the cells note : the outher transparent zone ; and the inner zone, 

 filled with zymogen granules. 1 : 1300. 



Fig. 3. Serous acinus of 

 the glands of Brennee of the 

 rabbit; iron haematoxylin. The 

 outer zone is indistinctly striated 

 (basal filaments — prozymogen) ; 

 the inner zone, clear and reti- 

 cular; a few only of the gra- 

 nules of zymogen are preserved. 

 1 : 1300. 



In the stained pre- 

 parations (Fig. 3) these 

 tubules are easily distin- 

 guished from the mucous 

 tubules by the fact that the 

 basal zone of the cell stains intensely and exhibits an indistinct radial 

 striatum (basal filaments). That the substance upon which this deeply 

 staining property depends is similar in chemical nature to the pro- 



