THE WONDERS OF LIFE 



and bones owe their peculiar property to the amount 

 and quality of the intercellular matter that is deposited 

 between the social cells. 



When the socially joined epidermic cells at the surface 

 of the tissue-bod}" thrust forth in common a protective 

 covering, we get the cuticles, which are often thick and 

 solid armor-plates. In many of the metaphyta wax 

 and flinty matter are deposited in the cellulose cuticles. 

 The strongest formation is found in the invertebrate 

 animals, where the cuticle often determines the whole 

 shape and articulation, as in the calcareous shells of 

 mollusks (mussel-shells, snail-shells, cockle-shells, etc.); 

 and especially the coats of the articulata (the crab's 

 coat of mail, and the skins of spiders and insects). 



