TRANSLATOR S PREFACE. XI 



insufficient supply of nutritious contents, and an inca- 

 pacity on the part of the mother to provide for their 

 complete development ivithin her own substance — are 

 rapidly hatched, give birth to imperfect offspring, which, 

 in proceeding to their definitive characters, undergo 

 severed alterations in structure and form, Jcnoivn as 

 m etamorphoses. 



The above are the most important results of the 

 inductive reasoning which the author employs, and 

 we have given an idea of their nature, because they 

 are not only the most striking, but are also those 

 upon which our opinions are in exact coincidence. 

 When, however, Professor de Quatrefages intimately 

 associates metamorphosis and geneagenesis, we can- 

 not agree with his conclusions ; and when he assumes 

 that vital operations are not to be explained by a 

 reference to the known laws of force as it exerts 

 itself through matter, and are only explicable on the 

 supposition of a " vital power," we must decidedly 

 express our dissent. We merely mention these cir- 

 cumstances in order to guard the reader against the 

 impression, that the translator of a treatise upon 

 science implies, by his silence, an assent to the 

 doctrines therein enunciated. 



In introducing this volume to the English Natural 

 History world, we believe that we are filling a gap 



