156 Inez Whipple Wilder. 



development which results in laying down the anlage of a glandular 

 mass consisting of many compact lobes. As development continues, 

 the tubular nature becomes more and more masked by the appearance 

 of alveolar distensions ; these appear first at the numerous bends in 

 the tubules and at the termini of the branches, and finally by a direct 

 foraiation of alveolar outpushings from the sides of the main tubules. 

 The resulting compact glandular mass thus acquires a pseudo-alveolar 

 structure, consisting of many complicated lobes, each with a central 

 tubule. 



In this process of development there occurs a gradual differentia- 

 tion of epithelial regions. Only the anterior portion, the duct of the 

 gland, retains the original low cubical epithelium which is charac- 

 teristic of the entire gland in its early stage. The remaining por- 

 tions of the glandular regions first seem to undergo throughout a 

 gradual change to a columnar form of epithelium. Then with the 

 development of regions with large lumina, the anlagen of the central 

 tubules of the adult gland, the epithelium of these distended regions 

 tends to become cubical again while the smaller branches retain their 

 columnar form of epithelial cells. 



While the main tubule is undergoing this complicated process of 

 development, the other tubules of the group are passing through a 

 more restricted development, often failing to exceed the condition of 

 simple tubules. They show, however, m their development, the 

 same tendencies that the main gland exhibits and in some cases become 

 somewhat complicated. 



As to the fate of these accessory tubules, we find in the example 

 given in Fig. 5, f, one case Avhere an accessory gland which has 

 attained a considerable size, becomes, by means of a secondarily 

 established communication, a part of the main glandular mass, while 

 at the same time its own duct suffers atrophy. It is possible, of 

 course, that accessory tubules may sometimes persist as independent 

 glands ; but inasmuch as in no case have I found more than a single 

 functional duct in any large adult specimen, I am of the opinion that 

 the more usual course is for the ducts, at least, of these accessory 

 glands to atrophy, the process extending also, possibly, to the glandidar 

 portion when this is small, while those which arrive at a considerable 



