Page:Popular Science Monthly Volume 28.djvu/102

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94
THE POPULAR SCIENCE MONTHLY.

if once the principle should be recognized. Hut this would be a matter of detail, which the different faculties would eventually settle, and there is no reason to fear that any faculty would long continue an elective system which experience should prove to disqualify students from choosing their subsequent studies intelligently.

What is needed, first of all, is the frank acknowledgment on the part of those who now control our colleges that these institutions are intended to furnish the means of higher education for all who are by nature fitted for it, and that, as long as there are divergent views held by men equally eminent, as to the proper preparation for the higher college studies, it behooves no one, who happens to be in power, to use his authority for the purpose of monopolizing the college for the application of his own theories. It is not from a wish to lessen Latin and Greek learning that the plea is made to treat other studies with equal liberality. There is no onslaught made on Latin and Greek, but, on the contrary, those who favor the monopoly of Latin and Greek are often guilty of making an unwarrantable onslaught on modern studies. The tendency of our colleges, in spite of the conservative element in them, is toward the breaking down of this monopoly. The increase of elective courses in all the prominent colleges is a most significant sign.


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ORIGIN OF COLOR IN ANIMALS.

By M. PAUL MARCHAL.

OF all the characteristics of organized bodies, color is one of the most fugitive. Trifling variations in the individual constitution, apparently slight changes in the biological conditions to which it is subject, are often sufficient to induce considerable modifications in the exterior coloration. Color in animals may, therefore, be regarded as having a variety of origins. Sometimes it is due to the fact that the tissues are formed from colored material; more frequently to their having imbibed a colored fluid. This is generally the case with the formations of the epidermis, the hairs of animals, the feathers of birds, and the scales of reptiles. The translucid nature of the teguments may also be the cause of external coloration, as in men of the white race, whose delicate skin exhibits the vessels of the underlying tissues. Many invertebrates are so transparent that their internal organs may be seen. In the majority of cases, animals owe their external hues to colored granulations or pigments, which, diffused through the tissues, give tints varying with their abundance or distribution. This substance may be black, or brown, or yellow in the vertebrates, while red, yellow, blue, and green predominate among the invertebrates. The phenomena of interference presented by their lami-