WHAT EVOLUTION IS 91 



two in number, and these are born 

 without gills and in full readiness 

 for terrestrial life. By keeping the 

 spotted salamander away from water, 

 Kammerer attempted to change its 

 breeding habits in the direction of 

 those of the black salamander. Such 

 artificially restrained salamanders re- 

 tained their young in their bodies till 

 the young had lost their gills and 

 were in a condition for life on the 

 land. The young of such parents 

 were reduced in number, as compared 

 with the normal number produced, 

 and were mostly black. In both these 

 respects the stock approached the 

 European black salamander. Spotted 

 salamanders, whose parents had thus 

 been modified in habit by experimen- 

 tal conditions, on arriving at sexual 

 maturity were, during their breeding 

 season, given access to water. They 

 deposited their young in the water at 



