28 BORDER LINES OF KNOWLEDGE 



D. The yellow elastic, fibrous element, the caout- 

 chouc of the animal mechanism, which pulls things 

 back into place, as the india-rubber band shuts the 

 door we have opened. 



E. The striped muscular fibre, — the red flesh, 

 which shortens itself in obedience to the will, and thus 

 produces all voluntary active motion. 



F. The unstriped muscular fibre, more properly 

 the fusiform-cell fibre, which carries on the involun- 

 tary internal movements. 



G. The nerve-cylinder, a glassy tube, with a pith 

 of some firmness, which conveys sensation to the brain 

 and the principle which induces motion from it. 



H. The nerve-corpuscle, the centre of nervous 

 power. 



I. The mucous tissue, as Virchow calls it, common 

 in embryonic structures, seen in the vitreous humor of 

 the adult. 



To these add X, granules, of indeterminate shape 

 and size, Y, for inorganic matters, such as the salts of 

 bone and teeth, and Z, to stand as a sjnnbol of the 

 fluids, and you have the letters of what I have ven- 

 tured to call the alphabet of the body. 



But just as in language certain diphthongs and syl- 

 lables are frequently recurring, so we have in the body 

 certain secondary and tertiary combinations, which we 

 meet more frequently than the solitary elements of 

 which they are composed. 



Thus A B, or a collection of cells united by simple 



