EMBRYOLOGY AND CLASSIFICATION. SOl 



furnishes us with a classification, to establish 

 which needs no arbitrary interference on the 

 part of the naturalist, since it is founded upon 

 natural evidence, both embryological and zoologi- 

 cal. While this is so obvious and easy among 

 Batrachians, I have no doubt, from the scanty 

 investigations I have already made, that Embry- 

 ology will in the end furnish us with the means 

 of recognizing the true affinities among all ani- 

 mals, and of ascertaining their relative standing 

 and normal position in their respective classes 

 with the utmost degree of accuracy and precision ; 

 but, before this can be done, we must be as fa- 

 miliar with the different stages of growth of the 

 young animals of all classes as we already are 

 with those of Batrachians, and shall probably 

 have to push our researches in directions not yet 

 dreamed of. 



Without entering into any details upon this 

 subject, I may as well state here, that among 

 Fishes I have lately discovered metamorphoses 

 as extensive as those known to take place among 

 Reptiles. Pisciculture being carried on upon 

 so large a scale in some parts of Europe, it is 

 surprising that the fact should not have been 

 ascertained long ago. This is perhaps owing to 

 the circumstance, that these metamorphoses be- 

 gin after the hatching of the young, at a time 

 when they are apt to die if reared in close con- 



