SECRETION IN GENERAL 



constructed with particular regard to the arrangement of the cells which has 

 just been described. 



Secreting glands are classified according to certain structural types, as: 

 i. The simple tubular gland, A, figure 247, examples of which are furnished 

 by the follicles of Lieberkiihn, and the tubular peptic glands of the stomach. 

 They are simple tubes of mucous membrane, the walls of which are lined with 



FIG. 247. Plans of Extension of Secreting Membrane by Inversion or Recession in the 

 Forms of Cavities. A, Simple glands, viz., g, straight tube; h, sac; i, coiled tube. B, 

 Multilocular crypts; k, of tubular form; /, saccular. C, Racemose or saccular compound 

 gland; m, entire gland, showing branched duct and lobular structure; n, a lobule, detached 

 with o, branch of duct proceeding from it. D, Compound tubular gland. (Sharpey.) 



secreting cells arranged as an epithelium. To the same class may be re- 

 ferred the elongated and tortuous sudoriferous glands. 



2. The compound tubular glands, D, figure 247, form another division. 

 These consist of main gland tubes, which divide and subdivide. Each gland 

 may be made up of the subdivisions of one or more main tubes. The ulti- 

 mate subdivisions of the tubes are sometimes highly convoluted. They are 



