THE MICROSCOPE IN ANIMAL HISTOLOGY. 209 



milk from the mammary gland; saliva, gastric juice and 

 pancreatic fluid for digestion ; mucus, sebaceous matter, 

 tears, etc. Excretions result from waste or decomposi- 

 tion, and are incapable of further use; as carbonic acid, 

 separated by the lungs ; urea, uric acid, etc., by the kid- 

 neys ; saline matters, from kidneys and skin ; lactic acid, 

 portions of bile, and some of the components of faeces. 



The sweat glands in the skin are simply convoluted tubes 

 lined with glandular epithelium and surrounded by a 

 basket-like plexus of capillaries. The sebaceous glands are 

 racemose, and often open into the hair-follicles. 



The salivary glands are complex mucous glands, anc} 

 the saliva secreted by them is a complex mixture. The 

 terminal nerves of the submaxillary gland have been traced 

 to the nuclei of the gland-cells. 



The lingual glands, and parotid, partake of the nature 

 of lymphoid organs. The glands of the oesophagus are 

 racemose. In the stomach there are two kinds, the peptic, 

 and gastric mucous glands. The peptic glands are blind 

 tubes closely crowded together over the mucous mem- 

 brane, lined with columnar epithelium near their open- 

 ings, and gland-cells below. The mucous glands are nu- 

 merous near the pylorus, and are usually branching tubes. 

 The capillaries are arranged in long rneshes about the 

 peptic glands, and form a delicate network in the submu- 

 cous tissue. Numerous lymphatic radicles communicate 

 with lymph-vessels below the peptic glands. 



The small intestine contains the racemose glands of 

 Brunner and the tubular follicles of Lieberkuhn, together 

 with the lymphoid follicles known as the solitary and 

 agminated glands of Peyer. The glands of Brunner are 

 confined to the duodenum, and their excretory duct and 

 gland vesicle are lined by columnar epithelium. Lieber- 

 kuhn's follicles are found in great numbers all over the 

 small intestine. Peyer's patches are most numerous in 

 the ileum. They are accumulations of solitary glands, 



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