ANIMAL GRAFTS AND REGENERATIONS. 333 



life ceased. Not long ago, Philippeaux noted the entire 

 restoration of the spleen in animals from which that organ 

 had been removed. 



Charles Legros, who has undertaken of late years many 

 interesting experiments upon regenerations, has discovered 

 that time takes an important part in these phenomena. 

 The tail of a lizard grows out again rapidly as to its out- 

 ward shape ; in two or three months the severed organ re- 

 appears with its usual length and thickness ; but the inte- 

 rior is unlike that of regular tails, containing, as it does, 

 nerves, muscles, and vessels, but no vertebrae. This text- 

 ure remains unaltered for a long time, and naturalists had 

 inferred from this that the bones of the lizard's tail are not 

 reproduced. Legros has watched the advance of develop- 

 ment in this organ for several years continuously, and has 

 noted the appearance of vertebras at the end of two years. 

 This savant experimented with green lizards. The re- 

 stored tail continued gray for a long time, and did not as- 

 sume the color of the rest of the body before the beginning 

 of the third year. . In another case Legros cut off the tail 

 of a dormouse at the beginning of winter. The wound 

 shaped itself into a sort of pad, which lengthened, became 

 covered with hair, and attained nearly the same length as 

 the original tail, which it surpassed in thickness. Un- 

 luckily, the animal's hibernation was not perfect ; it fre- 

 quently awoke, and at the end of three months it died. 

 There had been no opportunity for a complete restoration 

 of the inner parts of the organ. 



To these recent observations must be added those made 

 quite lately on the crawfish by Chantran. This skillful and 

 patient observer remarked that in the case of the crawfish the 

 antennas grow out during the time that intervenes between 

 one shedding, of the shell and the next, that is, in an inter- 

 val varying, according to the creature's age, from six weeks 



to six months. The claws and the tail-plates are also re- 

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