14 DIFFERENT TISSUES IN THE BODY. 



from the bodj. Otlier collections of bioplasm give 

 rise to bone, to nerve, to inuscle, and other tissues, 

 while from others, organs so delicate as the eye and 

 the ear proceed by gradual process of development, 

 and convince us of the marvellous and inexplicable 

 powers possessed by the formless bioplasm by which 

 alone any of them could be formed. At length all 

 the complex and elaborate forms of apparatus which 

 make up the body of a living creature result. These 

 excite our wonder the more thoroughly we study 

 them, whether in what Ave call the lower or the 

 higher creatures. These organs and structures per- 

 form their appointed work for the appointed time, 

 decay, and are resolved into formless matters of 

 interest to the chemist as well as to the anatomist 

 and physiologist. 



25. Difi'ei'ent tissues in the liody. — The body of a 

 hving animal is composed of many different tissues 

 performing very different acts, and designed from 

 the first to fulfil different purposes as proved by the 

 fact that each working tissue " has to pass through 

 several stages of formation, during none of which 

 does it work or serve any useful purpose. But these 

 stages of inaction were necessary for its construction ; 

 and the ultimate form it was to take, and the duty 

 it was to discharge, must have been delermiued from 

 the first, when it was without form, and when no 

 one could have premised either the form it was to 

 assume, the work it was to do, or say why it existed 

 at all. 



Bone and flesh or muscle, and cartilage or gristle, 

 cuticle, nail, and hair, nerve, fibrous tissue, are ex- 

 amples of diffei"ent tissues. The tissues of the body 

 change with age. The muscles of a young man are, 

 weight for weight, more powerful than those of an old 

 person or a young child. The tissues vary under dif- 

 ferent conditions. In health the same muscles and 

 nerves will do far more work without fatigue than they 



