on Dre on le a 
SS Ti ae 
THE PAXTTY OF SPECIES. 65 
in the potato plant. The small, almost worthless tubers 
of the wild potato have changed, under the force of 
intelligent cultivation, to the large, starchy, nutritious 
vegetables, which furnish so many people a large portion 
of their food. Mind has been at work; mind and na- 
ture have changed the size, the quality, the productive- 
ness of the solanum tuberosum; but neither mind nor 
nature, nor both combined, have, so far as we know, ever 
in the slightest degree changed the species. Potatoes 
are potatoes still, and always will be. The present law 
of vegetation is that intelligent cultivation of almost any 
plant will either change the original in one way or another, 
or, what is more likely, will produce several distinct 
varieties; but that all these changed forms are but mere 
modifications of the original species, and that, when de- 
prived of intelligent cultivation, thev all tend to revert 
to the original form. It is true that we see many and 
very diverse varieties of certain species, especially those 
that have received the most attention from the hands of 
man. The dog, for instance, exists as the great, shaggy 
Newfoundland or St. Bernard, or as the tight girted 
greyhound, as the petted poodle or the despised “yellow 
dog ;’”’ but in every case he is a dog, and not a wolf, and 
his fellow dogs recognize him as such, too. Hens differ 
amazingly; new breeds periodically come into existence 
and into fashion; but turn them loose, and they will all 
seek the barnyard, and soon your fancy breeds will 
become corrupt. They “revert to type.” By the ex- 
ercise of intelligent selection and training, man is able 
to emphasize certain points and to produce new breeds, 
but not to change the essential structure nor to alter the 
specific characteristics. The species are fixed. Huxley 
says: 
“If you breed from the male and female of the same 
race, you of course have offspring of the like kind, and 
