ON GASTEROPODA. 343 
had cut, not the entire head, but merely the tentacula and the 
jaw, but without leaving their roots, reproduced these organs, 
and he concludes that Spallanzani, in his amputations, only 
removed the cap or bonnet. 
M. Cotti, an eminent meteorologist, declared, that after 
numerous experiments made from 1768 to 1774, he was also 
obliged to conclude, that the snail whose head was completely 
amputated, did not renew it, but perished. Valmont de 
Bomare tried similar experiments about the same time, and 
with similar success. 
Nevertheless some persons were more fortunate, and among 
others, the celebrated Madame Bassi de Bologne, M. La- 
voisier, Scheeffer, &c. But the memoir which seemed to put 
the result of Spallanzani’s experiments out of doubt, was one 
inserted by Bonnet, in the “‘ Journal de Physique.” He in- 
sisted on the precautions which were necessary to be taken 
that the experiment might succeed. He accompanied his 
memoir with figures, to show the parts retrenched, and the 
manner in which they are reproduced by a sort of vegetation. 
We there find that he never cut any part but tentacula as far 
as their base, as well as the entire cap of the head and the 
jaw, and that the reproduction, which has some variations 
both with respect to time, and the order in which the organs 
are reproduced, does, nevertheless, really take place. Un- 
happily, he has not given us the anatomy of the organs 
which he retrenched, nor that of those which were reproduced, 
so that his experiments can scarcely yet be considered as 
conclusive. 
In 1788, M. O. Miiller published some experiments con- 
firmatory of those of Bonnet. He made use of very sharp 
scissors, and placed them obliquely, so as also to take away 
only the upper half of the head, that is, the four tentacula, the 
upper lip, the jaw, and sometimes a small part of the foot. 
Finally, some experiments on the same subject, and much 
