196 GEOLOGICAL BIOLOGY. 



sense, being groxvth with rcprodiictioji ; inheritance, which is 

 almost imphed by reproduction ; variability from the indirect 

 and direct action of the conditions of Hfe, and from use and 

 disuse ; a ratio of increase so high as to lead to a struggle 

 for life, and, as a consequence, to natural selection, entailing 

 divergence of characters, and the extinction of less improved 

 forms. There is a grandeur in this view of life, with its sev- 

 eral powers, having been originally breathed by the Creator 

 into a few forms, or into one , and that, whilst this planet has 

 been cycling on, according to the fixed laws of gravity, from 

 so simple a beginning, endless forms most beautiful and most 

 wonderful have been and are being evolved." * 



Do Characters become of Higher Rank as they are Transmitted ? 

 — The natural and general inference from the Darwinian ex- 

 planation of the origin of species is that variations, by selec- 

 tion and invariable transmission, become, in the course of 

 generations, fixed and permanent characteristics in the off- 

 spring, which removes them from the rank of variations to that 

 of specific characters ; by degrees in the course of more genera- 

 tions these same characters are supposed to become of higher 

 rank and constitute the generic characters of their descend- 

 ants; and in the same way further fixation and repeated in- 

 heritance might make them to become still more important, 

 and thus to attain ordinal and finally class rank in classification. 

 The paleontologist may with good reason ask if this be the 

 fact. Are early genera made up of species whose distinguish- 

 ing specific characters constitute the distinguishing marks of 

 genera of later times .? There are those who question the 

 truth of this proposition as a matter of fact. 



Evolution of Genera and Acceleration and Retardation The 



opinion was expressed by E. D. Copef that the evolution of 

 generic characters has proceeded in a different manner from 

 the evolution of specific characters; that the evolution of 

 generic and of specific characters has not he^n pari passu, but 

 independently of each other. He further distinguished two 

 special laws of evolution — the law of acceleration and retar- 

 dation, and the law of natural selection. 



* Pages 305, 306. 



f "Origin of the Fittest: Essays on Evolution," p. 43. New York, 1887. 



