CHAPTER III 



THE FINER STRUCTURE OF TWO TYPICAL ORGANS, 



GLANDS AND MUSCLES. THE CONNECTIVE TISSUES. 



THE LYMPHATIC SYSTEM 



In the previous chapter we have examined the general 

 construction of the human machine as regards its more 

 conspicuous parts or organs, and especially their location, 

 whether internal or external, dorsal or ventral, anterior or 

 posterior, on the right or on the left, their relations to 

 certain important cavities, and their combination to consti- 

 tute the mechanism which we call the human body. We 

 must now push our examination further and investigate 

 the finer structure of some of the more important parts of 

 the machine. For this purpose we may select two typical 

 organs, a gland and a muscle, the one unfamiliar, by name 

 at least, to most people, the other well known in the form 

 of steaks, chops, roast beef, and other meats. 



1. What is a gland? A gland is a mass of tissue, gen- 

 erally softer than muscle and of no special size or shape, 

 though often rounded or egg-shaped. The gland most 

 easily seen is the milk gland or udder of the cow. This 

 is a large mass of soft tissues devoted to manufactur- 

 ing or secreting milk. In general, glands are manufac- 

 turing organs for the preparation of saliva, gastric juice, 

 bile, tears, sweat, or other secretions. Some have tubes, 

 or ducts, through which their secretions are carried away; 

 others have no such outlets and hence are known as duct- 

 less glands. Glands vary in size from some which are 

 microscopic to the huge liver, which is the largest single 



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