734 THE POPULAR SCIENCE MONTHLY. 



the organic kingdom throughout geological history an evolution. This 

 is the point of discussion, and not only of discussion, but, alas ! of 

 heated and even angry dispute. The field of discussion is thus nar- 

 rowed to this third point only. 



Before stating the two opposite views of the cause of evolution, it 

 is necessary to remind the reader that when the evolutionist speaks of 

 the forces that determine progressive changes in organic forms as resi- 

 dent or inherent, all that he means, or ought to mean, is that they are 

 resident in the same sense as all natural forces are resident ; in the 

 same sense that the vital forces of the embryo are resident in the em- 

 bryo, or that the forces of the development of the solar system accord- 

 ing to the nebular or any other cosmogonic hypotheses are resident in 

 that system. In other words, they mean only that they are natural, 

 not supernatural. This does not, of course, touch that deeper, that 

 deepest of all questions, viz., the essential nature and origin of natural 

 forces ; how far they are independent and self-existent, and how far 

 they are only modes of divine energy. This is a question of philosophy, 

 not of science. 



As already stated, all will admit a grand resemblance between the 

 stages of embryonic development and those of the development of the 

 organic kingdom. This was first brought out clearly by Louis Agassiz, 

 and is, in fact, the greatest result of his life-work. All admit, also, 

 that the embryonic development is a natural process. Is the develop- 

 ment of the organic kingdom also a natural process ? All biologists 

 of the present day contend that it is ; all the old-school naturalists, 

 with Agassiz at their head, and all anti-evolutionists of every school, 

 contend that it is not. We take Agassiz as the type of this school, 

 because he has most fully elaborated and most distinctly formulated 

 this view. As formulated by him, it has stood in the minds of many 

 as an alternative and substitute for evolution. 



According to the evolutionists, all organic forms, whether species, 

 genera, families, orders, classes, etc., are variable, and, if external con- 

 ditions favor, these variations accumulate in one direction and grad- 

 ually produce new forms, the intermediate links being usually destroyed 

 or dying out. Accoi'ding to Agassiz, the higher groups, such as genera, 

 families, orders, etc., are indeed variable by the introduction of new 

 species, but species are the ultimate elements of classification, and, like 

 the ultimate elements of chemistry, are unchangeable ; and, therefore, 

 the speculations of the evolutionist concerning the transmutation of 

 species are as vain as were the speculations of the alchemists concern- 

 ing the transmutation of metals that the origin of man, for example, 

 from any lower species is as impossible as the origin of gold from any 

 baser metal. Both sides admit frequent change of species during geo- 

 logical history, but one regards the change as a change by gradual 

 transmutation of one species into another through successive genera- 

 tions and by natural process, the other as change by substitution of 



