SNAIL. 
595 
grow till it was equal in length to the other. He 
next proceeded to take off part of the head, which 
was attended with the same success; for in course of 
time the parts were reproduced, and the animal be- 
came as perfect as ever. This was not always the 
case when the whole head was removed ; but even 
under this unfavourable circumstance the animal 
often recovered, and appeared at the end of a few 
months with a new head in every respect equal to 
the old one. The Professor tells us that he tried 
this experiment on a great many snails, and that 
they retreated into their shells the moment after 
the operation, where they concealed themselves, 
and remained for many weeks, and even months, 
covering the mouth of their habitation with a whit- 
ish operculum, produced by the tenacious matter 
which exudes from the body. When forced to 
come out in thirty or forty days, for the purpose of 
examining their wounds, the naked trunks of some 
appeared without any marks of reproduction ; but 
others, if the weather had been warm, exhibited a 
fleshy globule towards the middle of the trunk, very 
soft, and of a whitish ash colour, in which there 
was no organization either within or without. How- 
ever, in eight or ten days more, a sensible change 
took place ; the globule became much larger, the 
rudiments of the lips were evident, as also those of 
the small horns, the mouth, the tongue, and a 
membranaceous substance fixed in the upper jaw, 
which proved to be the new tooth of the snail. 
These parts develop further, and grow more con- 
2 ft 2 
