MUCOUS MEMBRANES AND GLANDS. 



the primary arrangement of the gland is modified by subsequent 

 changes to such a degree that the original plan of its structure is 

 recognized with difficulty. The sexual glands are so highly special- 

 ized that in their development they deviate materially from the mode 

 of the formation of the typical secretory organs. * Ordinarily the 

 elaborating glandular cells are ectodermic and entodermic in origin, 

 while the basement-membranes and supporting tissues are meso- 

 dermic. 



