REPTILES. 



iiaiid and the right foot off a Urjre newt ; and a flream of 

 blood, as tliick as a hog's briille, continued fpouting 

 out nearly two minutes without intermiffion. Not only ' 

 did the animal fcem not in the Icaft enfeebled by the lofs of 

 blood, but, in fcarcely a quarter of an liour, to my great 

 furprife, it fwallowed two earth-worms." Spallanzani's 

 Trafts, V. ii. p. 367. 



The following narrative is extrafled as a fpecimen of 

 Bonnet's experiments. " On the 6th of June I cut off 

 the right arm and left leg of a large newt clofe to the body. 

 ( It fecms from the accompanying figure that the fedtions 

 palled through the femur and humerus refpeftively.) A 

 flream of florid blood fpouted a minute and a half from 

 each wound ; however, the veflels foon clofed, and the newt 

 was apparently as well as thofe unmiitilatcd. But it will 

 «afily occur, that it did not fwim with equal facility. Wlicn 

 about a month had elapfed, I began to perceive a papilla, 

 of a violet grey colour, near the edge of the trunk or lec- 

 tion. This was the origin of a new arm and leg, which 

 gradually increafed, and were quite perceptible, althouc;h 

 ftill very fmall, on the I4tli of July. The two papillae 

 grew more in length than in thicknefs : they became minute 

 Humps, and on the ift of Auguft were two lines long. 

 A kind of cleft hardly perceptible announces the appearance 

 of two toes : no cleft appears on the originating arm. The 

 new parts were very dillinguilhable from the old by their 

 lighter colour. The two toes were eafily recognifed on the 

 feventh : they were real miniatures, and truly moil minute. 

 The ilump of the arm had increafed, but there was no in- 

 dication of fingers. 



" It is pleahng to oblerve the little hand fully unfolding, 

 while only three fingers of unequal length are vilible : the 

 middle one is the longeit. The arm has made no fenfible 

 progrefs. The new foot had four toes alfo of unequal 

 length ; the firft and fecond of which are longeit ; the other 

 two only begin to appear ; the fourth is fcarcely percepti- 

 ble. Evolution advanced every.day. The regenerated mem- 

 bers began to deepen in colour, fo that the line, difcrimi- 

 nating the old parts from the new, was no longer fo con- 

 fpicueus ; but the black fpecks on the toes of unmutilated 

 newts were ftill imperceptible. On the 22d of Augull four 

 well-fhaped fingers were already on the hand ; but only four 

 toes out of the five v.hich the foot regenerates ; and they 

 all have to acquire more fize, confiltence, and colour. I 

 continued my obfervations on the daily evolutions of the 

 members ; and the following were their dimenfions in length 

 on the 30th of September. 



Old Members. New Members. 



Arm - 4 lines. Arm - 2-|lines. 



Cubit - 3^ Cubit - 2A 



Thigh. - 3 Thigh - 2^ 



Leg - 4 Leg - 2i 



Longcft finger 31- Longeft finger i\ 



Longeft toe - 4I Longeit toe - i j- 



Even in the beginning of Oftober, the fifth toe of the new 

 foot was not vifible." Lib. cit. 372, et feq. 



There is a kind of femi-tranfparency in the reproduced 

 parts, which the original members have not. This continues 

 long, and changes (lowly as the reproduftions colour. The 

 tranfparency is evidently greater on the edges of the fingers 

 than elfewhere ; if examined with a magnifier they feem in- 

 clofed in a fine diaphanous envelope : but nothing of this is 

 evident in the old fingers. (P. 376.) " It is incredible how 

 long the new fingers require to attain the fize of the old. I 

 have had newts, whole fingers, in thirteen months and more, 

 were not as largs as thofe of unmutilated members." 



(P. 393.) "When the tails of large newts were anipu^ 

 tated near their origin, the whole died in a certain time. 

 If the part be cut off about its middle, reproduftion will 

 follow. A tail was cut on the 1 ith of July, and on the 14th 

 of Auguft, the reproduced part was ibout three lines and a 

 half long, and four and a half in diameter at the bafe. The 

 new portion was ten lines in length on the 20th of September, 

 and Aiaped exactly like the tail of a newt. I could obferve 

 no difference betvpeen the motions of this regenerated tail, 

 and thofe of tails unmutilated. On the 5th of October the 

 regenerated part had a peculiar tranfparency, wanting in the 

 reft of the tail." P. 381, et feq. 



" The fingers and toes are not evolved in the fame pro- 

 portion as the arm and leg. Now, when I write this, on 

 the loth of Oftober, the new arm and leg of the newt, 

 mutilated on the 6th of June, have nearly attained the fize 

 of the original members, while the regenerated fingers and 

 toes have not acquired half their natural fize ; yet they 

 are perfeAly well formed, and execute all their funclions." 

 P. 390. 



Blumenbach found that the true falamandcr (lacerta fa- 

 lamandra) poflefTes the fame reproduftive power as the 

 water newt (lacerta lacuftris) : that a third part of the tail, 

 or a toe, would be perfedfly but very flowly reproduced, 

 and remained even at the end of a year confiderably inferior 

 in fize to that of the original parts. Specimen, p. 32. 



Bonnet made other experiments to determine whether 

 reproduced members poflefs the fame powers of reproduc- 

 tion as thofe amputated. He cut off an arm and a thigh 

 of a large newt on the 2d of June : as foon as the hand 

 and foot were vifible, he cut them off, and they were re- 

 newed : he repeated this four times, the lall operation 

 being on the 13th of Odober, and the parts were each time 

 reftoied. P. 394, et feq. 



He diflocaied the arms of one and the thighs of another 

 newt, fo that the members immediately after were pendent, 

 as if dead, the animal having no power over them. On the 

 following evening each newt moved the disjointed limbs with 

 a liberty and facility which announced that nature had al- 

 ready repaired the diiorder. P. 431. 



The moft furprifing faft in Bonnet's Memoir is the repro- 

 dudlion of the entire eye. " With a fcalpel," fays he, " I ex- 

 trafled the right eye of a large newt on the I3ih of Sep- 

 tember, 1779 > ^^^ ^ ^^^ '"5' obtain the globe without much 

 injury to the tunics. A deep bloody wound in the focket 

 of the eye was the confequence of this cruel operation. 

 And the reader will not be furprifed if I hardly expefted 

 any thing from it, and that the newt would probably re- 

 main blind for ever. How great was my aftonifiiment, 

 therefore, when, on the 3 1 it of May, 1 780, I faw a new 

 eye formed by nature. The iris and cornea were already 

 well fhaped, but the latter wanted its peculiar tranfpa- 

 rency, which is very confiderable in thefe animals. The 

 reftoration was complete on the ifl of September ; the 

 cornea being tranfparent, and the iris having acquired its 

 yellow gilded colour. On the 8th of November 1780, it 

 differed from the other eye only in being a little fmaller, 

 and in the iris, or golden circle, going only half round the 

 ball." P. 432, et feq. 



" I repeated," fays Blumenbach, " the experiments of 

 the celebrated Bonnet, concerning the reproduftion of the 

 eye in the water newt. I cut out the whole glol)e, at 

 the infertion of the optic nerve, in three inftances, in 

 neither of which was the organ reproduced : but a white 

 and firm fungus, (hooting from the cut end of the nerve, 

 gradually filled the orbit, the animals ihemfelvcs becoming 

 affected with a kind of diopfical fwelling, and dying in a 



ftVf 



