1897] ORIGIN OF SPECIES AMONG PLANTS 171 
dependent upon geological catastrophes for producing variations in 
plants and animals? Indeed, this would seem to be Darwin’s view 
in his discussion on geologic time, in which he says:—“It is 
probable, as Sir W. Thomson insists, that the world at a very early 
period was subjected to more rapid and violent changes in its 
physical conditions than those now occurring; and such changes 
would have tended to induce changes at a correspondiug rate in the 
organisms which then existed.”4 
But when we find that one species will change into another 
_ recognised species under our very eyes, if its environment be altered, 
‘why need one appeal to millions of years for aid? Dr Wallace, 
e.g., notes how “ Arabis anchoretica has tissue-papery leaves due 
to its growth in hollows in the rock. Seeds of this plant when 
cultivated at Kew produced the common species 4, alpina. The 
same thing occurs with many plants as every cultivator knows.” ” 
Darwin and Dr Wallace agree in requiring “ rapid adaptation,” 
but Darwin admits “that natural selection generally acts with 
extreme slowness.” ® 
Now, if nature has to wait for catastrophes before some 
‘changed conditions of life” come to her organisms, is not this 
something like trying to bring the mountain to Mahomet, instead 
of letting Mahomet walk to the mountain? Which is easier to 
do, to let plants and animals migrate to a place with a different 
climate and abundance or deficiency of altered food, rather than 
imagine the latter to come to them ? 
Migration is so obvious a process that Darwin cannot help 
alluding to it, as when he says :—“ Among animals which unite for 
each birth and are highly locomotive, doubtful forms ranked by one 
zoologist as a species and by another as a variety, can rarely be 
found within the same country, but are common in separated areas.” 4 
They have not, therefore, arisen at one common spot. 
A new climate and abundance of food are often supplied by 
domestication and cultivation, and the anticipated results follow, 
viz., variation ad libitum, the consequences also being often heredi- 
tary as they are in nature. 
Acquired Characters are Hereditary in Plants—Dr Wal- 
lace writes :—‘“ Climate and Food undoubtedly produce modifications 
in the individual, but it has not yet been proved that the modifications 
are hereditary. If this could be proved the whole discussion on 
the heredity of acquired characters would be settled in the 
affirmative.”® But surely cultivation proves it every day? Our 
garden vegetables are all derived from wild plants, and they come 
true by seed. 
2 
1 ‘Origin, etc.,” p. 286. ? Natural Science, vol. v. p. 182. % ‘‘ Origin, etc.,” p. 84. 
p Ongin, ete.,” yp. 37. 5 “Darwinism,” p. 489. 
