GENERAL STRUCTURE OF ANIMALS. 



13 



mal body is made up of cells as completely as a brick 

 building is made up of bricks; but as we may have 

 different kinds of brickwork adapted for various pur- 

 poses, so we have various kinds of cell work, and these 

 constitute the different tissues. The kinds of tissues are 

 more numerous and more varied as the functions are 

 more numerous and higher, and consequently as we rise 

 in the scale of organization. Therefore they are more 

 numerous and varied in animals than in plants, and in 

 the higher than in the lower animals. It would be use- 

 less and confusing to speak of all the kinds of tissues 

 treated in special works on his- 

 tology. We shall treat of six 

 general kinds, although some of 

 these will be subdivided. 



1. Connective. — This con- 

 sists of transparent white inter- 

 laced fibers or bands of fibers 

 running in all directions, forming 

 sometimes a loose mesh, some- 

 times a closely felted structure, in 

 which are found scattered spindle- 

 shaped nucleated cells with continuing branching fibers 

 (Fig. 4). It is called connective because it penetrates 

 and supports — it connects, and yet separates, all the 

 other tissues and organs of the body, forming a sort of 

 universal warp in which all other tissues are woven as a 

 woof determining the pattern of the fabric; so that if all 

 other tissues could be picked out and removed and this 

 one only remained, the whole form of the body with all 

 its organs would be retained in the connective tissue. 



Examples, — In skinning the dead body of an animal, 

 as we pull the skin from the underlying flesh we observe 

 a white shining mesh connecting them. This is divided 

 with the knife in the act of skinning. This is the subcu- 



Fig. 4. — Connective tissue. 



