14 THE STRUCTURE OF THE GLANDS OF BBUNNER 



tated in part on the cytoplasmic meshes, but not wholly so, because the network obtained 

 in muchaemateiu is formed by much larger, coarser meshes than that seen in the iron 

 haematoxylin preparation. Moreover, one may completely remove the substance stain- 

 able in muchsematein by treatment of the sections for several hours with a dilute solu- 

 tion of barium hydroxide. Subsequent staining in iron hsematoxylin shows that the 

 cytoplasmic network in the clear zones of the cell has undergone no change. 



We may now consider the changes exhibited by the cell while passing from the 

 intermediate state described in the foregoing paragraph to the fully loaded conditions. 

 As already pointed out, one may find in the same tubule cells in the different secretory 

 conditions, and by comparing cells from different tubules an idea may be obtained of 

 their secretory phases. The majority of the cells in Fig. 2 are in a condition inter- 

 mediate between the loaded and the discharged states. The completely loaded stage 

 is represented in Plate XX, Fig. 4, drawn from a tubule of a gland of Brunner of a 

 second opossum, stained with iron hasmatoxylin. In this preparation the cell presents 

 a swollen aspect and exhibits throughout a coarse meshwork of cytoplasm inclosing clear 

 secretion spaces. There is no indication of a subdivision of the contained secretion 

 into a proximal and distal mass, the transverse bridge of protoplasm seen in most of 

 the cells of Fig. 2 being here represented only by a slight thickening of some of the 

 cytoplasmic trabecula? in the middle of the cell. The cytoplasm at the base of the 

 cell, which was of considerable extent in Fig. 2, is here reduced to a minimum, and 

 the nucleus has in many cells taken on the crescentic form so characteristic of mucous 

 cells. The tubules of the gland in this individual were in general larger and the lurnina 

 narrower than in those from the first animal. An idea of the way in which this secretion- 

 loaded cell is derived from those of the type illustrated in Fig. 2 may be gained by 

 studying a large number of tubules from the same animal stained in iron hsematoxylin 

 and in muchsematein. It has been pointed out that in preparations stained with 

 muchasmatein without coming in contact with water the secretion appears in the form 

 of rounded granules arranged in two more or less distinct groups, and that the gran- 

 ules of the proximal mass are frequently smaller and less crowded than those of the 

 distal mass. The changes in the cell in the act of storing up secretion seem to be 

 going on more actively in this inner mass of granules which increases progressively in 

 density and extent by increase in the size of the granules and by addition of new 

 granules. Correlated with this increase in amount and number of the droplets of 

 secretion is a diminution of the amount of cytoplasm which takes place simultaneously 

 in the basal cytoplasm, in that of the transverse bridge, and in that of the inter- 

 granular trabeculae. The result is that the transverse bridge of cytoplasm presently 

 disappears and the two masses of secretion become continuous. At the same time the 

 amount of secretion in the distal zone is probably increasing, although this is less 

 easily made out. A comparison of the cells in the two extreme conditions stained in 

 iron hsematoxylin shows that the cytoplasmic network of the distal zone is composed 

 of larger meshes in the fully loaded cell. 



290 



