104 AMPHIBIA. 



water, described by Dr. Milne Edwards, the ureters do not terminate in the bladder, but 



formed by duplicatures of the lining mem- in the rectum itself." Dr. Grant states, that on 



brane of the branchial cavity. The eel too, as the contrary, "the bladder receives the ureters." 

 is well known, will live for a long time out of The kidneys are of a lengthened form, in the 



water, from its branchial cavity being capable of aquatic genera, but are shorter in the frogs and 



retaining a sufficient quantity of water to bathe other anoura. 



the branchiae for a considerable time, thus XIV. On the restoration of lost parts 



preserving those organs in a respirable state. The fact that parts lost by accident, or re- 



XIII. Of transpiration and of secretion. moved for the purpose of experiment, become 



The particular condition of the skin already reproduced in many of the lower animals, has 



described, naked and consisting of a moist been known for ages. The actual multipli- 



inucous surface, would render it probable that cation of the species in many, perhaps all the 



cutaneous transpiration should be exceedingly polygastric animalcula, by spontaneous sepa- 



extensive and rapid in these animals ; this is ration, that of the hydra by artificial division, 



in fact the case to such an extent, that when the restoration of lost arms in the different 



exposed to too great a degree of heat, the eva- species of asterias, of the anterior or posterior 



poration of transpired fluid is sufficient to pro- extremity of the body in the earthworm, of 



duce a very rapid decrease in the weight of the the claws of the lobster, and other Crustacea, 



animal ; which, if exposed for a sufficiently and of portions of the head in the pulmo- 



long period to its influence, becomes almost niferous mollusca, are, all of them, phenomena 



dried up and dies. which have attracted the attention, and occu- 



One object, and that not an unimportant pied the experiments of physiologists, at va- 



one, of the sensible transpiration of fluid in rious periods. The experiments of Plateretti, 



these animals, the frogs especially, is un- Spallanzani, Murray, Bonnet, and others, have 



doubtedly to preserve the skin in a condition shewn that it is not in the invertebrate forms 



fit for the performance of that cutaneous respi- alone that we are to look for this phenomenon, 



ration which has been described. But its still but that the amphibia, and even some reptilia, 



more obvious purpose is to afford a quantity of will reproduce either the limbs or the tail, 



fluid for evaporation from the surface, in order to when removed. This restoration of the tail 



reduce and equalize the temperature of the body in the saurian reptiles is indeed a common 



when exposed to a degree of heat, sufficient to occurrence, and it often happens that the new 



incommode or injure it. This will appear tail is double through the whole of the restored 



very reasonable when we reflect that these ani- length. 



mals will die in a few minutes, if placed in Of all the observers of this curious phe- 



water of 107 degrees of Fahr., though respiring nomenon in the amphibia, Bonnet* stands pre- 



freely with the head above the water, whilst, eminent for the laborious and patient zeal with 



on the contrary, they will support for hours the which all his experiments were conducted, no 



action of damp air of the same temperature. less than for the conscientious strictness with 



The water which is thus transpired is not which they are recorded. In many experi- 

 the result of the absorption of fluids taken in ments he cut off the anterior or posterior limbs 

 by the mouth, for these animals do not appear of the common water salamander or triton, 

 to drink. It is received by absorption on the which he found to be invariably restored, and 

 surface of the skin, to which part it is after- even the toes were reproduced, and acquired 

 wards restored when necessary. But in order some degree of motion. The tails were also 

 to be ready whenever circumstances call for its amputated at various distances from the base, 

 use, the fluid thus absorbed is conveyed into a and were always renewed. The same limb 

 membranous cavity, formed generally of two was in some cases removed and restored four 

 lobes, opening into the cloaca, where it is re- times consecutively. In all cases it was ob- 

 tained, to be again absorbed, and again con- served that warmth encouraged and that cold 

 veyed to the surface for the purposes just men- retarded the regeneration of the part. The 

 tioned. When a frog is suddenly alarmed, or restored portions were not generally well- 

 seized, it ejects from its cloaca a quantity of formed, but in some instances varied by excess, 

 pure, limpid water, for the purpose of lighten- in others by defect. One of the most extra- 

 ing itself, that it may leap with greater facility, ordinary results was that which followed the 

 This fluid is expelled from the sac in question, extirpation of an eye from one of these ani- 

 and is often mistaken for urine, and the sac for mals. In the course of a year this organ was 

 a urinary bladder. Hence, if a frog be kept in completely restored, and its organization was 

 a moist situation, without having access to found to be perfect. 



water in any form but in vapour, the skin is Dumeril records a remarkable experiment 

 always kept moist, and the water-bag always of this nature, in his latest work on the rep- 

 filled, tilia. The subject was the triton mar- 



Such is the function attributed in the first moratus. Three-fourths of the head were cut 



place by Townson to the sac in question, and off, and the animal was deposited at the bot- 



after him by Dumeril, Altena, and others ; but torn of a large vessel having half an inch depth 



Cuvier, Dr. Grant, and many other anato- of water, which was constantly renewed. It 



mists consider that it is the true urinary blad- continued to live, and to move slowly. The 

 der. That Townson's opinion is correct ap- 

 pears, says Altena, " from the circumstance that * CEuvres, in 4to, Neufchatel, 1769. 



