'k 



468 



Binneifs Monograph of the Helices 



may serve for the whole, and those of the European spe- 

 cies do not seem to differ in any considerable degree from 

 those of our own. 



The extraordinary power of reproducing some of their 



r 



members, and even the head itself, when mutilated, which 

 they were discovered to possess by Spallanzani, and the 

 promulgation of which fact was received with so much 

 doubt and incredulity by the learned,* exists also in our 

 species. The uncertain points of their history, such as 

 the question whether the black points on the end of the 

 superior tentaculae, which are generally considered to be 

 eyes, are true organs of vision, are equally matters of 

 doubt with us. The state of the question as to this par- 

 ticular, is somewhat singular. The anatomists, including 

 Swammerdam, Spallanzani and Bonnet, affirm that the 

 part in question is a true eye, possessing the structure 

 which in other animals is adapted to the sense of vision ; 

 while careful observers cannot distinguish, in the actions 

 of the living animal, any proof of their sensibility of hght 

 or consciousness of the presence of objects, except when 

 in actual contact with them ; and therefore infer, that they 

 are mere organs of touch. . The truth maj probably lie 

 between these extremes. These animals are nocturnal, 

 and pass the greater part of their lives under logs and 

 stones, or burrowing in the ground where but few rays of 

 light can reach them ; their eyes, adapted to such situa- 

 tions, may be merely rudimentary, and become useless in 

 the broad light of day. Besides, although the eyes are 



The controversy which arose on this subject caused a vast sacri- 

 fice of life among these animals. Adanson, one of many who called 

 the fact in question, acknowledged that he destroyed several thou- 

 sands in experiments. 



