378 REPRODUCTION OF LOST ORGANS. 



experiment often fails, and the mutilated animal may be 

 kept years in vain expectation of witnessing " this admi- 

 rable reproduction." A sufficient degree of heat is essential 

 to the, success. Temperate is not enough; and the heat 

 must be at least 61. 



The experiments of Spallanzani, made principally during 

 the spring and summer of 1766, raised curiosity to a high 

 pitch, and led to a very general decapitation of the snail 

 race. The results were confirmed by M. Bonnet, M. Tissot, 

 Father Barletti, H. Roos, M. Lavoisier, Turgot, Tenon, 

 Herissant, Miiller, Scarella, Schoeifer, Abbe Troilo, Sene- 

 bier, and by Signer Caldani, Girardi, and Pratalongo ; and 

 their accuracy was denied by M. Wartel, Father Cotte, M. 

 Valmont de Bomare, Argenville, Schroeter, Murray, Adan- 

 son, and Presciani. Adanson's opinion was given with cha- 

 racteristic confidence : " I have," he said, " as every one 

 has had, reproductions, even very immediate ones, of horns, 

 heads, lips, and other parts ; but these were reproductions 

 of parts that had not been entirely cut off : for all the heads, 

 I say, the real heads, all the horns, all the jaws, and the 

 other parts which have been completely cut away, and only 

 a quarter of a line from the origin, never exhibited any 

 kind of reproduction, far less a complete regeneration. Let 

 us be strict, and investigate the truth. All who have muti- 

 lated snails, and first Sig. Spallanzani, have certainly been 

 deceived. They have thought the head was severed when 

 the cap only has been cut off : they have believed that they 

 separated or eradicated the horns and jaws, while the origin 

 always remained ; whence it is not wonderful if reproduc- 

 tions ensued. These, you will candidly admit, are not re- 

 productions, or rather regenerations, such as you, Trembley 

 and Reaumur, had seen in fresh-water worms, the polypus, 

 the claws of lobsters. How many well-credited operations 

 have deceived persons, less familiar than us, with similar 

 operations and the anatomy of shelled animals. They have 

 thought that they had completely cut off so many heads, 

 horns, and mouths, .beyond the origin, which in every jour- 

 nal and periodical paper, they have so liberally regenerated. 

 I am well aware of our deficiency in most nice experiments ; 

 and, notwithstanding my great experience, I may almost 

 presume to say, dexterity in the anatomy of the smallest 

 animals, I always distrust myself. For this reason I have 

 repeated the same experiments an hundred and an hundred 

 times before hazarding the results before the public." But 

 neither this strong denial, nor other counter-evidence, can 

 rebut the positive experiments of Spallanzani ; and the 



