WHAT IS A SPECIES? 1 



PROFESSOR S. W. WILLISTON 



University of Chicago 



AVi. have had in the past not a few interesting discus- 

 sions upon or controversies over the methods of evolu- 

 tion and the origin of species in this club. We have more 

 or less plausible theories as to the evolution of species, 

 by natural selection, mutation, inheritance of acquired 

 characters, etc., but we have very nebulous ideas as to 

 what species really are. Nothing is more common than 

 the term species; nothing is more uncertain than what 

 species are. 



Long after the present topic had been suggested for 

 discussion by the club, I was delighted to learn of a like 

 discussion to be held at the late meeting of the Botanical 

 Society in Chicago. I anticipated that symposium with 

 the liveliest feelings of satisfaction, confidently expect- 

 ing a brilliant illumination of the whole umbrageous sub- 

 ject, an effulgence of light that would throw into deepest 

 obscurity whatever feeble beams I might myself hope 

 later to cast upon it. But lamentable was my disappoint- 

 ment. I heard some ancient platitudes that the zoologists 

 ceased in despair to consider a dozen years agone, and 

 many anathemas showered upon the botanical taxono- 

 mist. They berated him for making such a mess of classi- 

 fication, and hinted very freely that he didn't know much 

 anyhow, and probably never would. If all that was said 

 be true, then indeed the botanical taxonomists are a 

 sorry lot. One distinguished speaker declared they had 

 made no progress since the time of Linne, and he rather 

 seemed to desire that the whole tribe might be banished to 

 some desert isle where there is neither vegetable life nor 

 printer's ink, that they might no longer trouble the ecolo- 



