638 MUTATION THEORY OF PROFESSOR DE VRIES. 



that the mutation theory is as applicable to animals as to plants, and 

 the second, that the ratio of the mutability of species and, by implica- 

 tion, also, of the higher groups, varies in the course of their chrono 

 logical life history. It is necessary to mention here that according to 

 the mutation theory each newly originated species, while possessing 

 distinctly separate attributes, is never very widely different from the 

 parent form. Wide differences result from the extinction of inter- 

 vening species and repeated mutations; and because newly mutated 

 species may themselves be immediately mutative, wide differences may 

 occur in a comparatively short time. This view of the subject has an 

 important bearing upon the following remarks. 



The earliest known fossil faunas, those of the Cambrian age, 

 embrace remains representing live of the six animal subkingdoms, 

 namely, the Protozoa, Coelenterata, Annuloida, Annulosa. and Mol- 

 lusca. Furthermore, these fossil remains indicate a high degree of 

 faunal development, and proportionately wide differentiation in each 

 of those subkingdoms. That is, fossil remains of well-developed 

 faunas pertaining to all the animal subkingdoms, except the Vertebra ta, 

 are found in the earliest known fossiliferous strata of the earth; and 

 the occurrence of remains pertaining to those five subkingdoms in all 

 subsequent subdivisions of the geological scale shows that their 

 genetic lines have come down without a break to the present day. 

 We know absolutel}' nothing of any earlier life than that represented 

 by those Cambrian forms; and we must assume their sudden, or at least 

 rapid, origination, or, by applying the theory of natural selection, 

 construct an evolutional parallax that, by its inconsiderable angle, will 

 carry back the origin of life upon the earth to a chronological point 

 inconceivably remote. It therefore seems unreasonable to apply the 

 theory of natural selection to this case. 



The wonderful flora of the Carboniferous age stands out prominent 

 and unique from all the other known floras of the earth, and yet we 

 know little or nothing of its ancestry or of its genetic succession. Its 

 introduction and extinction were apparently too sudden and complete 

 to be satisfactorily explained by the theory of natural selection. 



The earliest known remains of the great subclass of dinosaurian 

 reptiles are found in the earlier Mesozoic strata, and the latest known 

 representatives of that subclass barely survived the close of Mesozoic 

 time. Those earliest dinosaurs existed in multitudes, and suddenly 

 became the ruling animals of the earth. A large proportion of them 

 were of titanic size, and the grade of their organization was of the high- 

 est of their class. The} 7 were differentiated into flesh eaters and plant 

 eaters and into denizens of land and water respectively. We know 

 absolutely nothing of their genetic origin; but their introduction upon 

 the earth was evidently so sudden and their differentiation so great 

 and various that the theory of natural selection is plainly insufficient 



