CHAPTER XIV 



CONCLUSION : THE CONGRUITY OF THE EVIDENCE 



IN not-living matter we have combinations of molecules of all 

 degrees of complexity — beginning with those entering into 

 the composition of the simple elements, and ending with the big 

 and highly complex components of various colloids. And seeing 

 that the so-called elements are built up by molecules composed 

 of different numbers of similar atoms, the difference between 

 elements and compounds simply depends upon the likeness or 

 unlikeness of the atoms entering into the composition of their 

 molecules. 



Thus molecular composition is an important item even with 

 reference to substances that are looked upon as elementary — 

 different modes of composition or arrangement of the atoms 

 of like kind sufficing to produce what are known as ' allotropic ' 

 states. It will be easily understood, therefore, that in compound 

 substances a greater and greater possibility of molecular rearrange- 

 ment arises in proportion to their atomic complexity. Gradually, 

 in fact, this atomic complexity becomes the all-important character 

 of a compound, and one to which the nature of the constituent 

 atoms is altogether subordinate. In proof of this, one has only 

 to refer to the multitudes of ' isomeric ' compounds having wholly 

 different properties, made up of carbon, hydrogen, and oxygen 

 in the same relative proportions, and to the enormous number 

 of other isomeric compounds resulting from the varying modes 

 of arrangement of a few definite elements. 



There can be no reasonable doubt that the form of a crystal 

 is a resultant necessity, predetermined by the molecular properties 

 of the matter composing it, and the sum total of conditions acting 

 thereupon at the time of collocation. 



Similarly, there are excellent reasons for believing that the form 

 and structure possessed by each simple organism is that which 



