Page:Popular Science Monthly Volume 62.djvu/489

Rh That the smaller species are created as such is the view now held by a comparatively small group of scientists. It is a contention, the truth of which has never been generally recognized, and at the present time has of course lost all right of existence. Before and after Linnaeus, before and after Darwin, the formation of the smaller species, the one from the other, has, except by the few above mentioned, been generally recognized, a recognition based upon experience as well as on tradition.

The smaller species are called subspecies or, as in horticulture, varieties, and are therefore considered as subdivisions of the species of Linnaeus.

Their descent from other species was conceded even before the days of Darwin, but nothing was known regarding the manner of their origin. It was generally deemed sufficient to attribute it to environmental influence. In agriculture and in horticulture it occurred from time to time that new forms originated from older ones; it always happened unexpectedly and without gradual transitions, always by skips and jumps. The new forms were called sports; whether in nature the same thing occurred was unknown.

Both in agriculture and horticulture these sudden changes were very rare and always shrouded in mystery. They occurred without any apparent preparation, the new form appeared unexpectedly, and once its presence had become apparent it was impossible to trace its origin. One could but state the fact, which, for cultivation-and trade-purposes, was deemed quite sufficient; but its nature remained wrapped in darkness. Truly no tempting basis on which to found a grand theory.

It was for this reason that Darwin preferred to turn to more generally known, or, at least, more tangible, facts. He laid much stress on over-production, on the struggle for life which must be the consequence, and on the greater chances of success possessed by the strongest individuals or by those best adapted to their surroundings.

He pointed to the dissimilarity, the so-called variability of individuals, and showed it might be met with everywhere and at all times, in all organs and in all characters. This dissimilarity is decisive in the struggle for life; not in every individual case of course, for here chance plays too prominent a part, but in the majority of cases and in the long run. That which is not fitted for the surroundings must succumb; each species adapts itself more or less to its environment; each species is different in nature from what it would be in the absence of all disturbing influences and were its reproduction unhampered.

How far can variability extend its influence? Has variability its limits? May variability proceed for centuries in the same direction or must it necessarily return to the starting point? Can variability bring about the formation of new characters or new organs or is it