12 EXPERIMENTAL EVOLUTION 



but other botanists, basing their estimate of species upon origins, 

 have reduced them or reincluded them into the form or type first 

 described. Consider the number of species which have been 

 made in the genus Citrus, comprising the various oranges, lemons, 

 limes, and the like. Recall the roses. The moss-rose and others 

 would be regarded as distinct species by any botanist if they were 

 found wild, and if they held their characters as tenaciously as they 

 do under cultivation. In fact, the moss-rose was long regarded as 

 a good species, and it was only when its origin began to be under- 

 stood that this opinion was given up. The earlier botanists, who 

 were less critical about origins than the present botanists are, made 

 species largely upon apparent features of plants, although their 

 fundamental conception of a species was one which was created, 

 as we find it, in the beginning. Yet, strangely enough, we at the 

 present day profess to regard species as nothing more than loose 

 and conventional aggregations of similar individuals, and which 

 we conceive to have sprung from a common ancestor at some 

 more or less late epoch in the world's history, — we make our 

 species upon premises which we deny, by giving greater weight to 

 obscurity of origin than we do to similarities of individuals. 



The fact is that much of the practice of systematic or descrip- 

 tive botany is at variance with the teachings of evolution. Every 

 naturalist now knows that nature does not set out to make 

 species. She makes a multitude of forms which we, merely 

 for purposes of convenience in classifying our knowledge of 

 them, combine into more or less marked aggregations, to 

 which we have given the name species. Now and then 

 we find in nature an aggregation of successive individuals, 

 which is so well marked and set off from its associated groups, 

 that we think nature to have made an out-and-out distinct 

 species ; but a closer acquaintance with such species shows that 

 in many cases, the intermediate or outlying forms have been lost, 

 and that the type which we now know is the remainder in a contin- 

 uous problem of subtraction. In other cases, it appears to have 

 arisen, without intermediate forms, as a distinct offshoot from an 

 older type. This is well illustrated in many remarkably distinct 

 garden forms, which originated all at once with characters new to 

 the species or even to the genus. I have mentioned such a case 



