GLANDS. 405 



they have been called gingival, in the uterus and vagina, where 

 they have been named uterine and vaginal glands : in the 

 stomach, also, where they are known as the lenticular glands, 

 they are very frequently wanting. 



There are also certain glands which have not been gene- 

 rally placed in the category of mucous glands, which, never- 

 theless, are really structurally identical with them : of this 

 nature, are Brunner's and Cowper's glands. 



From the preceding observation, it follows that Brunner's 

 and Cowper's glands should be described with the other mu- 

 cous glands : it will, however, be seen hereafter that the 

 former present certain resemblances to the tubular and the 

 latter to the lobular glands. 



Messrs. Todd and Bowman * regard the mucous glands as 

 identical in structure, and probably in function also, with the 

 salivary glands : that they are not salivary glands, however, 

 may be shown, first, by the anatomical differences which may 

 be pointed out as existing between mucous and salivary glands, 

 as well as, secondly, by the fact that mucous glands occur in 

 situations as in the trachea, &c. where they could serve 

 no purpose as salivary glands. Mucous glands occur in two 

 forms : a simple and compound form. In its simple or sim- 

 plest form, a mucous gland consists of a single duct in com- 

 munication, at its origin, with a saccated membrane, each 

 sacculus of which forms an imperfect follicle. In its com- 

 pound form, it consists of several ducts, each of which, at its 

 origin, is in like manner in connection with a bunch of in- 

 complete follicles. 



The chief anatomical characters which distinguish mucous 

 glands from the salivary, to which, indeed, they bear con- 

 siderable resemblance, depend upon the fact that, in the 

 mucous glands, the follicles are incomplete ; that is, they 

 open into each other and into a common central cavity, from 

 which the single efferent duct proceeds ; while in the salivary 

 glands each follicle is a distinct body of a rounded or oval 

 form, and provided with a small primary efferent duel. 



* Physiological Anatomy, page 182. 

 K K 4 



