REPRODUCE LOST ORGANS. 



377 



record. M. cle Quatrefages pressed specimens of an Eolis 

 between the compressor until the skin was ruptured and 

 the body, nearly emptied of its sarcode, was flattened 

 almost to a membrane ; yet on being replaced in sea-water 

 these individuals recovered perfectly. * And of the Tuni- 

 cata, we are told that "not unfrequently we find Salpae 

 making their way through the waters deprived of tlieir 

 nuclei by birds or fishes, retaining their vitality for a con- 

 siderable time, and exercising their muscular powers when 

 the organs of digestion, circulation, and reproduction have 

 been torn away." f 



The singular power the Mollusca have of reproducmg 

 organs which have been amputated was first determined by 

 the Abbe Spallanzani, who too often experimented without 

 a definite object in view, for the sake merely of satisfy nig 

 a cruel curiosity as to the result. He took snails (Helix 

 pomatia, nemoralis, and lucorum), and cut away the ten- 

 tacula either in part or wholly, and they were renewed in 

 about two months' time, perfect in all respects even to the 

 restoration of the eyes at their tips, with all its humours 

 and coats in their original integrity. "The snail," says 

 Spallanzani, " makes the same use of the new horns as it 

 did of the old, whether by protruding them from the head, 

 extending, contracting, or concealing them, or by display- 

 ing their acute and lively sensibility; so that on the most 

 gentle touch, they are suddenly withdrawn and put in 

 safety.":}: If the experiment is carried further, and the 

 half or the whole head amputated, the regeneration of the 

 parts is equally complete, a longer time being allowed for 

 the redintegration ; and you cannot reflect on this fact with- 

 out wonder, for in the head of this creature are placed its 

 organs of sense, the eye, the ear, and the feelers ; the brain, 

 the centre of its nervous system ; the mouth and its various 

 appendages, and a large mass of muscles ; yet all these 

 organs grow again to such perfection that they cannot be 

 distinguished from the original formations ! AH the cir- 

 cumstances requisite for the success of the experiment are 

 not well known. If adroitly conducted success in general 

 follows ; but under apparently the same circumstances the 



shortly after they had heen frozen." — Rai/ Reports oti Zoology, 1847, 

 p. 216. 



* Ann. dcs So. Nat. (1843) xix. 278 and 311. 



+ Forbes and Hanlcy, Brit. IMolhisca, i. 47. 



X Tracts on the Nat. Hist, of Animals and Vegetables, translated by 

 .T. G. Dalycll, ii. 228. I refer to this volume for a very complete history 

 of Animal Reproductions. 



