MANIFESTATIONS OF VITALITY 



19 



matter often go together to make up the form of an organism, 

 the lifeless matter being laid down either within the cells or 

 around the cells. Many products of waste metabolism are 

 thus stored up in living cells, perhaps to serve some useful pur- 

 pose in the functional activities, or to await some means of 

 disposal. Crystals are often found in cells (Fig. 7), and all 

 vegetable and some animal forms make and store up starch 

 grains, sometimes, as in the case of the potato, in great 

 quantities. 



FIG. 8. Lifeless matter around living cells, c, Cartilage cells surrounded by 

 lifeless matrix, m\ and branching bone cells in the lifeless bony matrix (at right). 

 (From Sedgwick and Wilson.) 



Fat also is stored up frequently in cells, and, like starch, be- 

 comes a reserve store of nutriment. Again, living cells secrete 

 about themselves different kinds of lifeless matter for purposes 

 of support, protection, defense, etc. Cartilage cells become 

 surrounded by a lifeless matrix of hard resistant cartilage, some 

 kinds of which become replaced by deposition of calcium phos- 

 phate and thus become bone with which the living cells of the 

 former cartilage are entirely displaced (Fig. 8). Similarly 

 living blood elements float in a lifeless matrix of fluid plasm. 

 Some products of living activity not infrequently become a 



