VOYAGE FROM NEW YORK TO RIO DE JANEIRO. 21 



nature ? I answer, Yes. The standard is to be found in 

 the changes animals undergo from their first formation 

 in the egg to their adult condition. 



" It would be impossible for me here and now to give 

 you the details of this method of investigation, but I can 

 tell you enough to illustrate my statement. Take a homely 

 and very familiar example, that of the branch of Articulates. 

 Naturalists divide this branch into three classes, — Insects, 

 Crustacea, and Worms ; and most of them tell you that Worms 

 are 4owest, Crustacea next in rank, and that Insects stand 

 highest, while others have placed the Crustacea at the head 

 of the group. We may well ask why. Why does an insect 

 stand above a crustacean, or, vice versa, why is a grass- 

 hopper or a butterfly structurally superior to a lobster or a 

 shrimp ? And indeed there must be a difference in opinion 

 as to the respective standing of these groups so long as 

 their classification is allowed to remain a purely arbitrary 

 one, based only upon interpretation of anatomical details. 

 One man thinks the structural features of Insects superior, 

 and places them highest ; another thinks the structural 

 features of the Crustacea highest, and places them at the 

 head. In either case it is only a question of individual 

 appreciation of the facts. But when we study the gradual 

 development of the insect, and find that in its earliest stages 

 it is worm-like, in its second, or chrysalis stage, it is crusta- 

 ccan-like, and only in its final completion it assumes the 

 character of a perfect insect, we have a simple natural scale 

 by which to estimate the comparative rank of these animals. 

 Since we cannot suppose that there is a retrograde move- 

 ment in the development of any animal, we must believe 

 that the insect stands highest, and our classification in this 

 instance is dictated by Nature herself. This is one of the 



