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fined to domesticated organisms. Among the millions of biolog- 

 ical systems many have wandered from the path of progressive 

 evolution and are on the way to extinction. As with the mo- 

 tions of the heavenly bodies, nature herself has deceived us, or 

 rather she has given us new riddles to read. 



The motion of species is not like that of the stars, in simple 

 geometrical figures. The evolutionary progress of species is 

 accomplished by the weaving of an intricate fabric of lines of 

 descent through the free interbreeding of the component organ- 

 isms. The simple, normal and typical constitution of a species 

 may be thought of as a huge but simple network of uniform 

 texture. All the organisms are diverse, but the diversity is 

 merely individual and indiscriminate, so that the network has a 

 uniform texture. 



THE SPECIFIC CONSTITUTION OF LIVING MATTER. 



Inorganic matter exists in a variety of conditions or physical 

 states, gaseous, liquid, colloidal, crystalline, granular or amor- 

 phous. The properties of matter depend upon these conditions 

 or states quite as much or more than upon the chemical com- 

 position or ultimate nature of the materials of which they are 

 composed. There are laws of gases, liquids and crystals be- 

 cause the different substances behave very much alike in the 

 same physical states. Indeed, the same physical states of dif- 

 ferent substances are generally very much more alike than the 

 different physical states of the same substance. 



In a similar manner the qualities of living matter are to be 

 associated and described with reference to its various states or 

 conditions. Chemically it is a mixture of water and of small 

 quantities of numerous substances and compounds. Physically 

 it is a jelly or colloid. Biologically it manifests such powers as 

 growth, digestion, motion and reproduction. Morphologically 

 it consists of cells or protoplasmic units with a more or less dif- 

 ferentiated internal structure, and a power to combine or asso- 

 ciate into organisms. 



For evolutionary purposes the chemical, physical and organic 

 points of view do not suffice. It is necessary to recognize that 

 living matter shows still another unique property, another kind 



