540' LOUIS AGASSIZ. 



For originality of material, clearness of pres- 

 entation, and beauty of illustration, these vol- 

 umes have had their full recognition as models 

 of scientific work. Their philosophy was, per- 

 haps, too much out of harmony with the cur- 

 rent theories of the day to be acceptable. 

 In the " Essay on Classification " especially, 

 Agassiz brought out with renewed earnest- 

 ness his conviction that the animal world rests 

 upon certain abstract conceptions, persistent 

 and indestructible. He insists that while phys- 

 ical influences maintain, and within certain 

 limits modify, organisms, they have never af- 

 fected typical structure, those characters, 

 namely, upon which the great groups of the 

 animal kingdom are united. From his point 

 of view, therefore, what environment can do 

 serves to emphasize what it cannot do. For 

 the argument on which these conclusions are 

 based we refer to the book itself. The dis- 

 cussion of this question occupies, however, 

 only the first portion of the volume, two thirds 

 of which are devoted to a general considera- 

 tion of classification, and the ideas which it 

 embodies, with a review of the modern systems 

 of zoology. 



aration, the reader is referred to the Preface of the volumes 

 themselves. 



