VI. 



Biological Theories. 



VI.— THE PHYLOGENY OF LUCERNARIANS. 



THE following speculation is now published, not only on account 

 of the intrinsic interest of the question suggested by the title, 

 but also as an illustration of the application of various views, already 

 published in this series of essays, to the solution of one definite 

 problem ; and I have deliberately chosen a case in which the 

 conclusion arrived at is the direct opposite (or converse) of the view 

 to be found in most modern zoological works which treat of the 

 subject. I have made this selection in order that anyone who is 

 prepared to give my views a fair test may do so by comparison of my 

 result with that reached by the usual methods and on the usual 

 assumptions. 



As it is necessary, in the course of the argument, to make use of 

 at least six views not as yet familiar to zoologists in general, I will 

 begin by enumerating those views, giving references to the papers in 

 the earlier volumes of Natural Science where fuller accounts of 

 them may be found. 



i. Heredity is a mere similarity or likeness among correspond- 

 ing individuals belonging to several generations of one species. 

 It is not a force or other objective influence, simple or complex, 

 capable of producing effects. The likeness between father and 

 son is not the effect of heredity ; it is heredity itself 

 (vol. i., p. 502). 



2. This similarity among individuals, or if we prefer to call it 

 so, this constancy of structure in successive generations, is the 

 result of Natural Selection. It is not simply an effect produced 

 once for all, but is dependent upon the continued action of 

 Natural (or other) Selection for its maintenance. Natural Selection 

 under constant environmental conditions tends steadily towards 

 the production of a constant structure, which, when it has become 

 almost constant, we speak of as the specific structure, and the 

 constancy of which may be called " heredity," though the abuse 

 of this term makes it safer to use only the term " constancy " 

 (vol. i., p. 578). 



3. Natural Selection is therefore, in a certain sense, independent 



p 



