348 SPARKS FROM A GEOLOGIST'S HAMMER. 



mals according to rank. All the terms of the series are 

 coexistent. This succession is taxonomic and simultaneous. 

 The first succession represents the grand march of the 

 animal kingdom as a whole; it is executed but once. The 

 second succession is an epitome of this, continually re- 

 hearsed in the life march of individuals. The third succes- 

 sion is one without relation to time or place; it is ideal; 

 it is a survival of traditions of the past, and condenses 

 the evolutions of ages into one present and perpetual 

 expression. PAL^EONTOLOGICAL history exhibits a series in 

 which the continued interpolation of newly discovered 

 terms produces the suspicion of a perfectly graduated and 

 genetic line. It suggests material continuity as a possi- 

 bility and a promise. MORPHOLOGICAL relations present such 

 continuity as something which, within the range of obser- 

 vation, is a fact, and beyond the range of observation is 

 a probability. The phenomena of VARIABILITY reveal a dis- 

 position and an aptitude on the part of nature to fulfill 

 the " promise," and make the " probability " completely a 

 " fact." The data of EMBRYOLOGY demonstrate that the de- 

 rivative relation of such terms as palaeontology presents 

 is an ever-repeated actuality. Now, with the work com- 

 pleted in the ontogenetic epitome, and with this proof 

 of nature's method, and the variational proof of nature's 

 method and means, it is little stretch of belief to grant 

 that nature pursued the method of derivative originations 

 during the whole period of palaeontological history. 



Now suppose it granted: (1) That geological history 

 presents us universally, series of nicely graduated forms; 

 (2) That these forms are all genetically related to each 

 other, and that consequently all living forms ai-e genetic- 

 ally connected. We have thus come to a knowledge of 



