94 THE POPULAR SCIENCE MONTHLY. 



if once the principle should be recognized. But this would be a mat- 

 ter 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 col- 

 lege studies, it behooves no one, who happens to be in power, to use his 

 authority for the purpose of monopolizing the college for the applica- 

 tion 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. 



OKIGIN OF COLOK IK ANIMALS. 



By M. PAUL MAEOIIAL. 



OF all the characteristics of organized bodies, color is one of the 

 most fugitive. Trifling variations in the individual constitu- 

 tion, apparently slight changes in the biological conditions to which 

 it is subject, are often suflficient to induce considerable modifications 

 in the exterior coloration. Color in animals may, therefore, be re- 

 garded 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 feath- 

 ers 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 under- 

 lying tissues. Many invertebrates are so transparent that their in- 

 ternal 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 dis- 

 tribution. This substance may be black, or brown, or yellow in the 

 vertebrates, Avhile red, yellow, blue, and green predominate among the 

 invertebrates. The phenomena of interference presented by their lami- 



