CHAPTER VI 



SOME FACTORS OF EVOLUTION : ORGANIC POLARITY AND MUTATION 



WE have seen how great are the tendencies to molecular 

 changes in all kinds of bodies, and how from its very 

 nature and the great complexity of the molecules entering into its 

 composition these tendencies ought to attain their maximum in 

 living matter — that is in protoplasm, the physical basis of life. 

 We have seen how in simpler forms of matter of the crystalloid 

 type, changes in molecular composition are often comparatively 

 easily brought about under the influence of changing conditions, 

 with the result that new crystalline forms as well as other new 

 physical properties are assumed by the matter in question as a 

 consequence of the altered polarities of their molecules. The same 

 kind of thing should hold good, therefore, for the different varieties 

 of living matter. This is frankly admitted by Herbert Spencer, 

 who says': — "These truths are not limited to inorganic matter: 

 they unquestionably hold of organic matter. As certainly as mole- 

 cules of alum have a form of equilibrium, the octahedron, into 

 which they fall when the temperature of their solvent allows them 

 to aggregate, so certainly must organic molecules of each kind, no 

 matter how complex, have a form of equilibrium in which, when 

 they aggregate, their complex forces are balanced — a form far less 

 rigid and definite, for the reason that they have far less definite 

 polarities, are far more unstable, and have their tendencies more 

 easily modified by environing conditions." 



This statement, and many others of a similar nature in the work 

 of Herbert Spencer, is in marked contrast with what is to be met 

 in the last and most elaborate work of Prof. Weismann, " The 

 Evolution Theory," which I have very carefully studied. On only 

 one single page (Vol. II, p. 152) have I found any mention of the 

 word ' isomerism ' ; while there have been no references to the 

 possibility of variations in forms of organisms being due to varia- 



• "Principles of Biology," Vol. I, Append. D. 

 96 



