DIRECT DEVELOPMENT. 211 



worm's eggs — that by the larval state the period of in- 

 fancy and weakness is prolonged, and the period of ma- 

 turity and efficient care for the continuance of the species 

 delayed, it follows that curtailments and reductions, con- 

 sequent on adaptation have, "as advantageous modifica- 

 tions, a prospect of perpetuation. As in Amphibians the 

 prolongation of the larval phase may be effected by 

 natural circumstances and artificial experiments, so in 

 like manner a compression of the phases of transforma- 

 tion, and a general curtailment of the metamorphosis 

 is imaginable. In the class of Amphibians we have, in 

 fact, several examples of curtailed and modified meta- 

 morphosis which bridge over the apparent chasm be- 

 tween development with and without transformation, and 

 render direct development comprehensible as being 

 gradually acquired. Amphibians will endeavour to ex- 

 tend themselves wherever they are invited by a sufficient 

 supply of insects, and the black salamander of the moun- 

 tains (Salamandra atra) has even overcome the impedi- 

 ment which might have been deemed insurmountable, 

 the absence of water for its larvae. It does not lay its eggs 

 like its congeners, but only two are received into the 

 oviduct, and the fluids secreted from its walls replace the 

 marsh to them and to the larvae which emerge from 

 them. Here, and not when separated from the parent, 

 do the gills make their appearance, while the other eggs, 

 gradually following, are devoured by the hungry larvae. 

 The metamorphosis of the black salamander, which has 

 lately been the subject of Fr. Marie Chauvin's remark- 

 able experiments, can be effected after exclusion, and 

 observation places it beyond a doubt that this is an in- 

 stance of adaptation to unusual conditions. . If the mode 



