ccxxii SECEETING GLANDS. 



adopted in the construction of secreting glands. The first degree is repre- 

 sented by a simple recess (fig. cxxvm., g, h), and such a recess, formed of 



Fig. CXXVII. 



Fig. CXXVII. PLAN TO SHOW AUGMENTATION OF SURFACE BY FORMATION OF 



PROCESSES. 



a, 6, c, as in preceding figure ; d, simple, and e f, branched or subdivided processes. 



secreting membrane, constitutes a simple gland. The shape of the cavity may 

 be tubular (g) or saccular (h), and, in either case, it is called indifferently a 

 crypt, follicle, or lacuna, for these names have not been strictly distinguished 

 in their application. Examples of these simple glands are found in the 

 raucous membrane of the stomach, intestines, and uterus. The secreting 

 surface may be increased, in a simple tubular gland, by mere lengthening of 

 the tube, in which case, however, when it acquires considerable length, the 

 tube is coiled up into a ball (fig. cxxvm., i), so as to take up less room, and 

 adapt itself to receive compactly ramified blood-vessels. The sweat-glands, 

 already described, and the ceruminous glands of the ear are instances of 

 simple glands formed of a long convoluted tube. But the great means adopted 

 for further increasing the secreting surface is by the subdivision, as well as 

 extension, of the cavity, and when this occurs the gland is said to be com- 

 pound. There is, however, a condition which might be looked on as a step 

 between the simple and compound glands, in which the sides or extremity 

 of a simple tube or sac become pouched or loculated (fig. cxxvm., k, I). 

 This form might be named the multilocular crypt. 



In the compound glands, the divisions of the secreting cavity may assume 

 a tubular or a saccular form, and this leads to the distinction of these 

 glands into the " tubular," and the " saccular," or " racemose." 



The racemose compound glands (fig. cxxvm. c) contain a multitude of 

 saccules, opening in clusters, into the extremities of a branched tube, 

 named the excretory duct. The saccules are rounded, pyriform or thimble 

 shaped, and then often named "cseeal." They are, as usual, formed by 

 a proper or basement membrane, and lined, or often rather filled, with 

 secreting cells ; they are arranged in groups, round the commencing 

 branches of the duct, into which they open both terminally and laterally 

 (fig. cxxvm. c, n) ; or it might with equal truth be said that the branches 

 of the duct are distended into cluhters of saccular dilatations. The ulti- 

 mate branches of the duct open into larger branches (o), these into larger 

 again, till they eventually terminate in one or more principal excretory 

 ducts (m), by which the secretion is poured out of the gland. It is from 

 the clustered arrangement of their ultimate vesicular recesses that these 

 glands are named "racemose" (in German " traubenformige Driisen") ; and 

 they, for the most part, have a distinctly lobular structure. The lobules 

 are held together by the branches of the duct to which they are appended, 

 and by interlobular connective tissue which also supports the blood- 

 vessels in their ramifications. The larger lobules are made up of smaller 

 ones, these of still smaller, and so on, for several successions. The 



