■50 



SCIENCE. 



[N. S. Vol. XII. No. 289. 



of individuals that have been called species 

 should have been ultimately all but per- 

 sonified, and ei'ected into something sup- 

 posed to have been realities, divinely estab- 

 lished and immutable. Even those of us 

 who have not passed middle age were alive 

 when, as one of my geological friends has 

 expressed it, a Species was treated almost 

 like a thing that had legs and could walk ; 

 and even the younger of us have seen the 

 idea grow, from Darwin and Wallace and 

 Huxley and Gray, through the scientific 

 circles into the world at large, that heresy 

 and atheism are not necessarily implied in 

 the belief that existing species are de- 

 scended from different earlier species, and 

 that their descendants, in all probability, 

 will be considered as yet other species. 



If the incident had been closed with a 

 general acceptance of this idea of the muta- 

 bility of species, we should probably have 

 been spared some trouble which we are now 

 experiencing and which we are actively 

 accumulating for transmission to our fol- 

 lowers on the stage ; but the change in the 

 theoretical way of viewing the question of 

 species has involved many practical changes 

 in the way of treating them. 



In some pliable groups, the expert plant 

 breeder is quite willing to take an order for 

 a non-existent garden form that differs as 

 much from all of the named and classified 

 plants as one species does from another in 

 nature, and, though he may not give a 

 bonded guaranty that it will not revert to 

 some other form after a few years, it is 

 quite likely to transmit its characters for a 

 considerable if indefinite time if bred true, 

 a condition less readily applied in the 

 garden than among species in a state of 

 nature, but scarcely more negligible in the 

 one case than in the other. Whether or 

 not we are to call the most distinct culti- 

 vated forms, some of which have been 

 deliberately evolved by the gardener and 

 some of which have originated as sports or 



sudden variants of either wild or cultivated 

 plants, species, is rather a matter of agree- 

 ment than anything else, for such as are 

 capable of perpetuation by ordinary natural 

 means constitute, in fact, groups of similar 

 individuals of common origin, reproducing 

 their kind, which is about all that can be 

 said now of natural species. 



The growing knowledge of the great and 

 immediate plasticity of species has led to a 

 considerably greater change in the way of 

 viewing them in the abstract than even 

 that which the introduction of evolutionary 

 views caused. That virtually left them as 

 real concepts, though it opened a vaguely 

 distant question as to their beginning and 

 end ; but this brings the beginning and end 

 so close together as to cast doubt upon the 

 existence of species at all as definable 

 groups having any considerable stability in 

 time. 



I can distinctly recall the thrill of sur- 

 prise with which, in my student days, I 

 heard of the belief of a distinguished Ger- 

 man professor, that species as known in 

 other plants and animals probably did not 

 exist among the bacteria. I felt grateful 

 later that the American flora contains fewer 

 representatives of Hieracium than are found 

 in Europe, when I saw the desperate efforts 

 that the Germans have made to distinguish 

 these difBcult plants ; and the polymorphism 

 of the European brambles made apparent 

 equal reason for thankfulness that American 

 institutions are simpler also in that genus. 

 But the rehabilitation of synonyms and va- 

 rieties in all groups that the last decade has 

 witnessed, and the increasing rapidity with 

 which the species- splitting knife is falling 

 upon Antennaria, Sisyrinchiuni, Viola, Cratce- 

 gus and many other genera, have removed 

 any such misguided thankfulness, and the 

 further separability of natural plants, even 

 on the old lines of specific delimitation, ap- 

 pears to be coming into as strong evidence 

 on the one hand as the gardener's power to 



