ROBERT RUSSELL BENSLEY 49 



SOLGEB, B. " Das Prozymogen (Bensley) der menschlichen Glandula submaxillaris." 69. Ver- 



handl. d, Gesellsch. deutsch. Naturf. u. Arzte, Braunschweig, Teil II (1898), p. 240. 

 STOHB, P. " tlber Riickbildung von Duodenaldriisen." Festschr. d. phys.-med. Gesellsch., 



Wiirzburg, 1899, pp. 207-14. 

 THEOHARI, A. " Existence de filaments basaux dans les cellules principales de la muqueuse 



gastrique." Compt. rend. Soc. de biol., Paris, Ser. XI, Vol. I (1899), pp. 341-3. 

 WEPFEB, J. J. Cicutae aquaticae historia et noxae. Basileae, J. R. Konig (1679), 336 pp. 



(Quoted after Oppel.) 

 ZIMMEBMANN, K. W. "Beitrage zur Kenntniss einiger Driisen und Epithelien." Arch. f. 



mikr. Anat, Bonn, Vol. LII (1898), pp. 546-51. 



EXPLANATION OF FIGURES 



For the drawings, of which Figs. 1-11 and Fig. 13 are reproductions the author is indebted 

 to the skill of Mr. Leonard H. Wilder. All drawings are from camera lucida outlines. 



PLATE XIX 



FIG. 1. Section including a portion of the pars pylorica ventriculi and the upper end of the 

 duodenum of the opossum, showing the peculiar defect of the tunica mucosa on which the 



glands of Brunner open. X 40. 



PLATE xx 



FIG. 2. Transverse section of two tubules of the glands of Brunner of the opossum. 

 Ferric alum hnematoxylin. The drawing shows the structure of the cells composing these 

 tubules in the condition of incomplete loading. The secretion is subdivided into a proximal 

 and distal mass by a band of cytoplasm. Some basal cytoplasm still remains at the attached 

 end of the cell and around the nucleus. X 1100. 



FIG. 3. Transverse section of a tubule of the glands of Brunner of the opossum in the 

 same physiological condition as those in Fig. 2, stained with stronger muchsematein. The 

 granular character of the secretion, its subdivision into two masses, and the clustering of the 

 granules of the proximal mass around the oval or flattened nucleus are well shown. X 1100. 



FIG. 4. Tubule of the gland of Brunner of the opossum in the condition of maximum 

 loading; iron hsematoxylin. The two masses of secretion are not to be recognized, the trans- 

 verse band of cytoplasm separating them having disappeared; basal cytoplasm less than in 

 Fig. 2; nucleus more flattened. X 1100. 



PLATE xxi 



FIG. 5. Portion of a lobule of Brunner's glands of the rabbit, stained in iron haema- 

 toxylin. The figure shows nine mucous tubules and one serous acinus in transverse section. 

 In the former the subdivision of the secretion into two masses is indicated in most of the cells. 

 X 500. 



FIG. 6. The serous acinus shown in Fig. 5 more highly magnified. In each cell the 

 outer zone filled with deeply staining prozymogen and the inner clear zone containing a few 

 granules of zymogen are shown. Most of the zymogen granules which are present in the 

 living cell have been lost in fixation. X 1300. 



FIG. 7. Fresh serous acinus from the rabbit's glands of Brunner showing inner zone filled 

 with zymogen granules. X 1300. 



FIG. 8. A tubule of Brunner's glands of the opossum. The section has been treated with 

 water and then stained with stronger muchsematein. The granules visible in Fig. 3 have given 

 place to a deeply stained coarse-meshed network. X 1100. 



325 



