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enemies or food, and even travel all around in the 

 body, often leaving it altogether. 



BODY TISSUES 



The animal body contains five forms of tissues: 

 Epithelial, in which the cells are very compact, 

 forming either thin or thick plates ; the connective 

 tissue, by which many organs are supported or 

 embedded ; muscle tissue, either smooth or striated, 

 and in which the cells are in fibers that contract 

 and shorten ; nerve-tissue, that has to do with nerve 

 and ganglion cells by which mental impulses are 

 sent; and blood and lymph tissue or fluid tissues. 



The first group is intimately connected with the 

 secretory organs, or those organs which secrete 

 certain substances essential for the proper work of 

 the body. Thus we have salivary glands, mucous 

 glands, sweat glands, and the liver and pancreas. 

 Connective tissue includes fibrous tissue, fatty tis- 

 sue, cartilage and bone. The fibrous connective 

 tissue is illustrated when the skin is easily picked 

 up in folds. Fatty tissue occurs where large 

 amounts of fat are deposited in the cells. Cartilage 

 is found where a large amount of firm support is 

 required. With muscle we are all familiar; it is 

 the real lean meat of the body. 



Blood and Lymph. — The blood is a fluid in 

 which many cells are to be found. The fluid is 

 known as serum or blood-plasma and the cells as 

 corpuscles, and are both red and white. The red 

 cells give the characteristic color. When observed 

 under a microscope, they appear as small, round 

 disks. They are of great importance to the body 

 work. Because of the coloring matter in them the 

 oxygen of the air is attracted when it comes in 



