Page:Popular Science Monthly Volume 43.djvu/506

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490
THE POPULAR SCIENCE MONTHLY.

tion preceding that of Weismann? and why he presents these difficulties to me more especially, deliberately ignoring my own hypothesis of physiological units? It can not be that he is ignorant of this hypothesis, since the work in which it is variously set forth (Principles of Biology, §§ 66-97) is one with which he is well acquainted: witness his Scientific Evidences of Organic Evolution; and he has had recent reminders of it in Weismann's Germ-plasm, where it is repeatedly referred to. Why, then, does he assume that I abandon my own hypothesis and ado[)t that of Darwin, thereby entangling myself in difficulties which my own hypothesis avoids? If, as I have argued, the germ-plasm consists of substantially similar units (having only those minute differences expressive of individual and ancestral differences of structure), none of the complicated requirements which Dr. Romanes emphasizes exist, and the alleged inconceivability disappears.

Here I must end: not intending to say more, unless for some very urgent reason, and leaving others to carry on the discussion. I have, indeed, been led to suspend for a short time my proper work only by consciousness of the transcendent importance of the question at issue. As I have before contended, a right answer to the question whether acquired characters are or are not inherited, underlies right beliefs not only in Biology and Psychology, but also in Education, Ethics, and Politics.—Contemporary Review.

 

THE COLOR CHANGES OF FROGS.
By Prof. CLARENCE M. WEED.

ONE who, with observant eye, leisurely paddles among the water lilies of an inland lake must often notice how closely the colors of the various frogs resting upon or among the lily pads resemble their environment. In the open sunshine, where light green is the prevailing tint, the colors of the frogs closely approximate it, but in the dark and shady recesses of the forest-bordered banks the batrachians are dull, deep brown, with darker spots scattered over their bodies. These are the effects as seen from above. If one were to dive beneath the water and look upward, he would see in either case only the whitish undersides of their bodies and legs—if, indeed, these were visible against the general lightness of the upper world.

It is evident that this resemblance to environment might result in either of two ways: first, the light-colored frogs might seek the light surroundings and the dark ones the dark surroundings; or, second, the frogs, provided they had the power, might