FIRST LECTURE. 



THE VARIATIONS AND MUTATIONS OF THE 



INTRODUCED SPARROW. PASSER 



DOMESTICUS. 



{A SECOND CONTRIBUTIOX TO THE STUDY OF VARIATION.) 



HERMON C. BUMPUS. 



In the preface to the second volume of these Lectures it is 

 stated that one of the leading objects of the course is "to 

 bring forward the unsettled problems of the day, and to discuss 

 them freely." The question of the adequacy of natural selec- 

 tion is one that at the present time still divides two schools of 

 speculative biology, and is a question that can be solved only 

 by those inductive methods which it is the function of a 

 Biological Laboratory to suggest, adopt, and execute. 



The principle of "Panmixia," or the "suspension of the pre- 

 serving influence of natural selection," has formed an integral 

 part of the speculative writings of Weismann, and, as part of 

 his theory of " the continuity of the germ-plasm," is presumed 

 to explain adequately the reduction of useless organs, and the 

 occurrence, especially among domesticated animals, of " the 

 greater number of those variations which are usually attributed 

 to the direct influence of the external conditions of life." 



This view of the regressive power of natural selection was, 

 at the time of the original presentation of Weismann's essay 

 ('83), not entirely new to science. Lankester ('90) calls atten- 

 tion to the fact that, eleven years earlier, in 1872, Darwin, in 

 the sixth edition of the Origin of Species, had the identical 

 principle in mind when he wrote: "If under changed condi- 

 tions of life a structure before useful becomes less useful, its 



