MUSCULAR TISSUE. 17 



forms the whole substance of the lowest animals, and in 

 the higher animals it not only connects as well as separates 

 organs, but also enters largely into their structure. It is 

 tliis tissue which forms mainly the skin, and also the 

 mucous and other membranes of the animal body. It 

 en sheathes the muscles and the bones, and is the tissue in 

 which gelatine is accumulated for the formation of the car- 

 tilages, and the mineral substances for the formation of the 



^5 * 



bones themselves ; and it constitutes almost the whole sub- 

 stance of the ligaments and tendons; and it is among its 

 meshes that the fat of the body is accumulated (Fig. 12). 

 In a word, it has been shown by anatomists that so com- 

 pletely does this cellular or connective tissue invest and 

 enter into all the organs of the body, even of the highest 

 animals, that if all the other tissues could be removed 

 without disturbing this one, a perfect model of all the or- 

 gans would be left, composed of this tissue alone ! 



Muscular tissue constitutes the part of the animal body 

 which is called the flesh or muscles that is, the parts 

 familiar to every one as lean meat. This tissue is com- 

 posed of fibers which have the property of contraction. 



There are two principal kinds of muscle the striated 

 and the unstriated muscle. 



Striated muscle includes all the ordinary muscles of the trunk and 

 limbs of the Vertebrate animals. It consists of bundles of fibers, each 

 FIG. 15. Fio. 16. 



Primitive bundle of muscle magnified 350 End view of Fig. 15, 



diameters, partly separated into disks. more magnified. 



bundle of which is made u^> of smaller bundles, and so on, until the 



