36 GENERAL ANATOMY. 



cavity which constantly, or at times, is in communication by 

 canals or immediately with the surface of the body. The most 

 simple are round vesicles (cells) clear as water, of 0*01 to 0'03 

 of a line diam.. formed of a structureless membrane, with granu- 

 lar contents and closed, lying in the substance of the mucous 

 membrane, without elevating it. Similar, but larger, are the gl. 

 tartaricss of the gums, gl. agminatse and solitaries of the small 

 intestines and the egg in the ovary. They open at times. We 

 therefore distinguish simple (gl. simplices, cryptse) and compound 

 glands (gl. compositse), and among these gl. conglomerate, which 

 form a mass, with one or few excretory ducts, and gl. aggregate, 

 which only lie close together, and possess separate excretory 

 ducts. Forms of glands : 



a. Glands like blind sacs consist of a series of vesicles opening into one 

 another, the first of which is closed, whilst the last opens upon the mucous 

 membrane or into an excretory duct. The shortest are the glands of Lie- 

 berkiihn in the small intestines, filled with viscous granular contents; they 

 are longer upon the large, particularly in the rectum. More in clusters, but 

 unarranged, appear the gl. pyloricce (gastric fluid glands), the gl. MeibamiancR 

 of the eyelids, and the glands of the canmcula lacrymalis. Wound up like a 

 ball of thread, convoluted: sweat glands of the skin and the ceruminous of 

 the ear. 



b. Glands in the form of a bunch of currants, racemose; are so composed, 

 that single vesicles are united into one lobule with a common excretory duct. 

 The primary lobules are associated together by uniting tissue into larger 

 secondary, and these into tertiary, which all communicate by the common 

 trunk of the entire gland only. The whole gland possesses a more or less 

 condensed covering of uniting tissue, never a serous. These racemose glands 

 are distinguished from one another, only, by their mass, size, and the rami- 

 fications of their excretory ducts. The lacrymal, mammary, and prostate 

 glands are remarkable, since in them a common excretory duct is wanting, 

 and the mass of several gland lobules appears joined together. Besides these 

 and the accumulated (gl. conglobata) Tonsillae, to this class belong the small 

 mucous glands of the lips and cheeks, of the palate, tongue, and oesophagus; 

 of the Larynx, Trachea, Bronchi, gl. Brunneriance of the small intestines, the 

 mucous glands of the Vagina; the salivary glands, the Pancreas; gl. Cowperi 

 and Bartholiniante. 



c. Reteform glands consisting of tubes (therefore gl. tubulosce), which, like 

 the blood-vessels, are united by anastomoses into a network, and never or 

 rarely terminate blindly, being, besides, many times convoluted. Their 

 excretory ducts open into bladder-like receptacles for the secretions (as in 

 the liver). To this class belong the kidneys and testicles. They are sur- 

 rounded by a fibrous membrane, which in the last sends septae inwards, so 

 that the lobules may be distinguished. 



The vessels of the glands are very numerous. In the Liver, Kidneys, and 

 Testicles they pass in and out at the Hilus; in the rest of the glands they 

 are distributed from different points upon the surface, since they follow the 

 uniting tissue between the lobes, lobules, and tubules. 



Nerves form plexuses upon the arteries, and accompany these into the in- 

 terior of the glands. 



