1895.] Experimental Evolution Amongst Plants. 323 
is so well marked and set off from its associated groups, that 
we think nature to have made an out and out distinct spe- 
cies; 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 continuous problem of subtraction. In other cases, it ap- 
pears 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 in the Upright tomato. Even 
the sudden appearance of these strange forms is proof that 
species may originate at any time and that it can be no part 
of our fundamental conception of a species that it shall have 
originated in some remote epoch. Species-making forever en- 
forces the idea of the distinctness and immutability of organic 
forms, but study of organisms themselves forever enforces an 
opposite conception. The intermediate and variable forms 
are perplexities to one who attempts to describe species as so 
many entities which have distinct and personal attributes, 
So the garden has always been the bugbear of the botanist. 
Even our lamented Asa Gray declared that the modern gar- 
den roses are “too much mixed by crossing and changed by 
variation to be subjects of botanical study.” He meant to say 
that the roses are too much modified to allow of species-mak- 
ing. The despair of systematic botanists is the proof of evo- 
lution ! 
I repeat that mere species-making, in the old or conven- 
tional sense, is an incubus to the study of nature. One who 
now describes a species should feel that he is simply describ- 
ing a variable and plastic group of individuals for mere con- 
venience’ sake. He should not attempt to draw the boundary 
lines hard and fast, nor should he be annoyed if he is obliged to 
modify his description every year. This loose group may con- 
tain some forms which seem to be aberrant to the idea which he 
has in mind; and it would seem as if he should be ready to call 
them new or distinct species whenever, from whatever cause, 
they become so much modified that it is convenient, for purposes 
