GLANDS. 87 



rior of its lobules and lobes, and convey to them, at 

 the same time, their blood-vessels and nerves. 



The vessels terminate in a rich web of capillaries J e e r s v 6 ^ 8 and 

 which is spread out upon the external surface of the 

 vesicles. The nerves ramify with the larger vascular 

 trunks of the gland, but do not appear to reach their 

 terminal secreting pouches. We know little or no- 

 thing of the sources of distribution of the lymphatics. 



To this first type are assimilated the salivary glands 

 and mucous follicles which belong to the cavities of 

 the mouth, pharynx, and oesophagus, the glands of 

 Brunner in the duodenum, the lacrymal glands, the 

 mucous follicles of the conjunctiva, vagina, and vulva, 

 the glands of Bartholinus and Cowper, and, finally, 

 those clusters of vesicles which have been mentioned 

 as imbedded in the walls of the ducts of the liver, 

 pancreas, and lung. 



The Lungs. The bronchial tubes, as is well known, Lung* 

 form a tree, whose principal branches are given off 

 from their trunks at an acute angle, whilst their ter- 

 minal ramifications are detached from the penultimate 

 branches at right angles. On examining the walls of 

 these little terminal ramifications upon their internal 

 surface, they are seen to be full of minute openings, 

 which lead into cavities (primary lobules), measuring 

 about aVth of an inch in mean diameter, and which 

 present a somewhat complicated structure. Each of Primary iobui e . 

 these primary lobules resembles one of the lungs of 

 the frog ; on its inner surface we recognise large 

 depressions, or partially formed vesicles (PL XIX. 

 fig. T. 1), each divided into three or four secondary 

 vesicles (fig. I. 2), which open by large orifices into 



