No. 49.1] 



WHAT IS A SPECIES? 



real truth; that incompetent and inexperienced taxono- 

 mists shall be ruled out of court, even as incompetent 

 anatomists and cytologists are disbarred. The unfortu- 

 nate thing is that we taxonomists have so bound our- 

 selves in a snarl of laws and by-laws that we are com- 

 pelled to incubate and wet-nurse every premature and 

 monstrous taxonomical imbecility till it dies a natural 

 death, whereas those of other biologists are promptly 

 strangled or thrown out into the cold to die of inanition. 

 Let us hope that we may escape from some of that snarl, 

 or at least that we may cut some of the bonds which hold 

 us too tightly. 



To discuss our subject in all its details and bearings 

 and from all view-points would require, not one evening, 

 but many. Permit me, therefore, to offer for your con- 

 sideration certain axioms of evolution— theories or hy- 

 potheses if you prefer to call them such— bearing more or 

 less closely upon the question, What is a species! Some 

 or all may be familiar to you— I do not know whether all 

 have beeen in print 6r not— but, such as they are, they are 

 all based upon my own observation, and, so far as that 

 goes, I am prepared to defend them, and will endeavor to 

 do so later if there are any you repudiate, as perhaps 

 there are. 



1. The only biological entity is the individual, and the 

 individual is inconstant. 



2. The value of specific characters is dependent upon 

 a number of interrelated and inseparable factors, the chief 

 of which are environment and heredity. 



3. Accumulated heredity may outweigh natural selec- 

 tion or environment, and vice versa. 



4. A crescent phylum is more variable, more plastic 

 than a long established one; that is, time is always an 

 element in the fixation of characters and the limitation of 

 variation, and the length of time is dependent more or 

 less upon the strenuousness of environment and selection, 

 and the plasticity of the type. 



5. New phyla arise from crescent phyla, never from 

 decadent or even dominant ones. 



