Sentence:  They think they can turn him into something rich and strange —turn him in a single generation—even as certain ingenious experimentalists turned what Nature meant for a <WSD>land-salamander</WSD> into a water-salamander, with new ruddertail and gills instead of lungs and feet suppressed, by feeding him with water animals in oxygenated water and cajoling his functions. 
Meaning of the word marked with <WSD> tags:  A salamander (Order "Caudata") that habitually or permanently lives its life on land.