ANIMALS AND THEIR ENVIRONMENTS. 319 



regarding the influence of surrounding conditions, not merely 

 on living beings in the present but in their past history as 

 well. Dumeril, thinking that excision of the gills might 

 induce the change of form, cut off these organs in the 

 axolotls, but without obtaining a successful result; the 

 animals simply producing new gills in virtue of the power of 

 replacing lost parts so common in their class. But Fraulein 

 von Chauvin, by dint of care and patience, succeeded in 

 enticing five specimens from their native waters by gradually 

 inuring them to a terrestrial existence. The animals were 

 highly refractory as far as their feeding was concerned ; but 

 their objections to diet when under experimentation were 

 overcome by the ingenious method of thrusting a live worm 

 into the mouth ; whilst by pinching the tail of the worm, it 

 was made to wriggle so far down the amphibian's throat, 

 that the animal was compelled to swallow the morsel. Of 

 the five subjects on which the patience of Fraulein von 

 Chauvin was exercised, three died, after a life of nearly fifty 

 days on land. At the period of their death, however, their 

 gills and tail fins were much reduced as compared with the 

 normal state of these organs. The two surviving axolotls, 

 however, behaved in the most satisfactory manner. Gills 

 and tail fins grew " small by degrees and beautifully less," and 

 apparently by an actual process of drying and shrivelling 

 through contact with the outer air, as opposed to any internal 

 or absorptive action. The animals moulted or shed their 

 skins several times ; and finally, as time passed, the gills and 

 tail fin wholly disappeared ; the gill-openings became closed ; 

 the flattened tail of the axolotls was replaced by a rounded 

 appendage ; the eyes became large ; and ultimately, with 

 the development of a beautiful brownish-black hue and gloss 

 on the skin, varied with yellow spots on the under parts, the 

 axolotls assumed the garb and guise of the land-amblystomas. 

 It was thus clearly proved that a change of surroundings 

 represented by the removal of the axolotls from the water, 

 and by their being gradually inured to a terrestrial existence, 

 has the effect of metamorphosing them into not merely 



