22 The Mechanism of Evolution in Leptinotaesa 



evolution. We all know to what use Spencer, Darwin, Weismann, and De Vrieff 

 have put this conception in the production of their theories, but Darwin, 

 Weismann, and De Vries figured their factorial elements in the gamete as single- 

 bodies, the carriers of the characters of the organisms. Each of these bodies, in 

 the terms of these writers, was potentially a small organism. Any such con- 

 ception eliminates the possibility of investigation from an experimental poiat 

 of view, and is certainly of an order which can not be formulated ia any physical 

 terms. There is no known instance in which a substance is the carrier of a 

 character, and all characters which appear in non-living substances are the 

 reaction products of the combiuing factors of composition and the conditions- 

 of the medium at the time of combination. 



Out of the neo-Mendelian investigations there has come the most valuable 

 contribution to biological science in a long time, namely, the exact demonstra- 

 tion that the characteristics of organisms are the product of the action of two 

 or more productive agents, and the Mendelian operations have clearly shown 

 that these factors may be removed one from the other, and that one may be 

 removed and the other left, thereby producing the non-appearance of the char- 

 acter with which the original pair is associated, and that the character may be 

 brought iato existence again when the missing one is replaced by the action of 

 crossing. This gives an opportunity to apply this principle further to the 

 analysis of organic constitution and to evolution problems. In this report the 

 principle is applied broadly and ia divergent lines, in every respect confirming 

 thus far the broad fundamental principles which are the outgrowth of a long 

 series of antecedent studies. And thus we may reformulate our conceptions of 

 organic constitution and evolution, that the organism itself in its gametic 

 make-up is but the associate combination of an unknown number of non-living 

 factors the iuteraction of which in many associated relations is necessary for the 

 production of the living substance and its characteristics. Any change in char- 

 acters which the organisms tmdergo are of the same order and due to the same 

 causes as are characteristic of changes in non-living substances. The method 

 of change of each of these characteristics is entirely the product of the factors, 

 their presence or absence within the system, and their iateraction with the 

 factors within and without; likewise the facts of survival or conservation, of 

 equilibration, and of all the processes present in evolution are directly and 

 solely to be investigated and solved from the standpoint of the genetic factors 

 within the non-genetic factors without the organisms. 



I realize that it will be contended that while this may apply perhaps with 

 some truth to the superficial characteristics, it can not apply to those long-time 

 trends of evolution and to the problems of fixity of type within phyla. As a 

 matter of fact the conception does give a naturalistic conception of these por- 

 tions of our problems. In the non-living world are found combinations of 

 various factors of composition which are most marvelous and tenacious in their 

 association. Silica and oxygen form an association — quartz — which is dis- 

 sociated with difficulty and one which persists for a long period of time. This 

 substance becomes the basis of many minor operations in producing the various 

 kinds of quartz — silicates and their products — which are produced by minor 

 additions or combinations of the basic combination of SiOj, and this might 

 perhaps be the equivalent in a rough sense of the general phyletic type of 

 organisms which when analyzed show certain securely combined gametic factors. 



