Ill REGENERATION TEMPERATURE 6^ 



Tlie same applies to the larvae of vh'iparous species, e.g. i>ala- 

 mandra atra, which, when cut out of the uterus and put into 

 water, soon cast off their long, tender gills and produce a stronger 

 set. In an Axolotl,^ two years old, a hand was cut off. After 

 four weeks there was a conical stump ; after the sixth week this 

 stump had two points ; in the eleventh week three or four 

 fingers were discernible, and a week later the complete hand. 

 Frequently these creatures reproduce five instead of the normal 

 four fingers. But the more proximal the cut, the more liable is 

 the new limb to reproduce supernumerary fingers, or even extra 

 hands and feet. Complete regeneration of the limb, cut off in the 

 middle of the humerus, took place within five months. 



Triton taeniatus, adult, reproduces cut fingers within five or 

 six weeks, and if the hand be cut above the carpus, new finger- 

 stumps appear in about one month. Grotte has observed that an 

 adult Proteus did not completely reproduce its whole leg imtil 

 after eighteen months ; and, according to Spallanzani, more than 

 one year elapses before the limb, bones, and cartilages of Triton 

 regain their normal strength. 



The Anura are likewise capable of regenerating their limbs, 

 the more readily the younger the specimens. For instance, in 

 a tadpole of Rana temporaria, in which the fore - limbs were 

 still hidden, the hind-limb, cut at the middle of the thigh, 

 reproduced nineteen days later a knee, followed by a short two- 

 toed stump. Ultimately the whole limb became completed. The 

 tail of tadpoles regenerates very quickly and completely, even 

 if it be cut off shortly before the final metamorphosis, when the 

 tail would in any case be reduced. Metamorphosed Anura have 

 almost entirely lost this faculty, but not absolutely. I myself 

 have kept two specimens of Rana temporaria, Avhich, when 

 already adult, had each lost a hand at the wrist. First there 

 was only the clean-cut stump with a scar, but within a year this 

 changed into a four-cornered stump, and two of the protuber- 

 ances developed a little further, reaching a length of about 4 mm. 

 These specimens lived for four years without further changes. 



Temperature. — Amphibia, like Fishes and Eeptiles, are, as 

 a rule, classed as cold-blooded animals, in opposition to the warm- 

 blooded Birds and Mammals. This distinction is one of degree 

 only. The terms poikilothermous and homothermous (7roLKiXo<i, 

 1 Barfurth, Aj-ch. Entwickmech. I. 1895, \>. 117. 



