THE LAWS OF LIVING PROTOPLASM 23 



bones come into existence? The cartilage grows 

 until it becomes bone. These changes are numer- 

 ous and known in minute detail. But the bone 

 is a different material and it must have come from 

 somewhere. The answer to this query leads to a 

 still more fundamental question, namely, the dis- 

 tinction between living, organic growth and non- 

 living, inorganic growth. 



Hills, valleys, sand-bars and crystals are all said 

 to grow. It is well to compare the growth of a 

 crystal with the growth of protoplasm, i, crystals 

 grow only in a highly saturated solution of mate- 

 rial like the crystal itself; while living things can 

 grow in a weak nutritive solution; 2, this nutritive 

 solution does not contain the chemical compounds 

 found in the living cell, while in the case of the 

 crystal, the substance of the crystal and its nutri- 

 tive solution , must be chemically identical; 3, 

 growth in living things leads to the reproduction 

 of more living things, while growth in inorganic 

 nature never does. LeConte tells the significance 

 of organic growth in the following condensed sen- 

 tence, which we may designate "The Law of 

 Growth" : "Organic life manufactures materials 

 like itself out of materials wholly different from 

 itself, and then uses the product for growth." 



Aristotle directed attention to this problem of 

 growth, but It was not definitely formulated until 

 Wolff, in 1774, published his studies in Embry- 



