126 MICROSCOPICAL OBJECTS FOUND 



How cautions must we then be in advancing any 

 conclusions relating to temperature and climate, 

 as well as to the geological age of rocks from such 

 comparatively uncertain data. To use the lan- 

 guage of a distinguished writer, in his well-merited 

 criticism of a very different work from any of these 

 which have rendered so illustrious the names of 

 Ehrenberg and D'Orbigny, " We may explain 

 the obscure cases of nature's work by appealing 

 to the clear — but do not let us stultify what is 

 clear, by starting with the obscure."* So, in 

 like manner, we must not cloud the evidence 

 afforded by the higher animals, with that 

 derivable from beings so much lower in the 

 scale of organization, and which, as a whole, are 

 so far removed from the influence of external 

 agencies. The study is at once so novel and so 

 fascinating, that all who pursue it, impressed by 

 its singular interest, are in danger of being 

 allured by it beyond the bounds of caution, — a 

 tendency which is ever promoted by the an- 

 nouncement of comprehensive hypotheses and 

 splendid novelties. 



* Re\dew of the Vestiges of the Natural History of Cre- 

 ation. Edin. Review, No. 165, p. 65. 



