110 HISTORY OF CRUSTACEA. CHAP. XI. 



CHAPTER XL 



ON THE PROGRESS OF EVOLUTION. 



FROM this scarcely unavoidable but unsatisfactory side- 

 glance upon the old school, which looks down with so 

 great an air of superiority upon Darwin's " intellectual 

 dream " and the " giddy enthusiasm " of its friends, I 

 turn to the more congenial task of considering the de- 

 velopmental history of the Crustacea from the point of 

 view of the Darwinian theory. 



Darwin himself, in the thirteenth chapter of his book, 

 has already discussed the conclusions derived from his 

 hypotheses in the domain of developmental history. 

 For a more detailed application of them, however, it is 

 necessary in the first place to trace these general con- 

 clusions a little further than he has there done. 



The changes by which young animals depart from 

 their parents, and the gradual accumulation of which 

 causes the production of new species, genera, and 

 families, may occur at an earlier or later period of life, 

 in the young state, or at the period of sexual ma- 

 turity. For the latter is by no means always, as in 

 the Insecta, a period of repose ; most other animals 

 even then continue to grow and to undergo changes. 



