ON GASTEROPODA. 345 
smooth, or cicatrized, in the same way as it is in partial am- 
putations. How they could avail themselves of the nutriment 
which Tarenne placed at their disposal, till the new head ap- 
peared, does not appear. Although Spallanzani has given 
fewer details respecting the operatory process which he pur- 
sued, than M. Tarenne, we find that he had already really ob- 
tained the same results, as the latter is candid enough to avow. 
From all this, it would certainly appear established, that the 
entire head of the helices can be regenerated when cut off, and 
yet, notwithstanding, we cannot quite get rid ofa certain degree 
of repugnance to admit this assertion as an indubitable fact. 
It is with difficulty that we conceive how the nervous threads, 
the muscles, the vessels which have been cut through the 
middle of their length, can re-accord with the portions which 
sprout from the head, now become a sort of germ; or, ad- 
mitting that the regeneration should proceed from the nervous 
and muscular threads themselves, how should the nervous 
threads shoot forth and give birth to the brain. To render 
our conviction complete, it would be necessary that the re- 
produced head should be carefully dissected, and compared 
with the one which was cut off. 
If the advantages which we derive from the helices are but 
inconsiderable, it is otherwise with regard to the detriment, or 
at least the inconvenience which they occasion us. All per- 
sons occupied in gardening regard them as a sort of plague. 
In fact, when these animals are abundant, they can lay waste 
ina single night an entire plantation of oleraceous herbs, a 
little time after they have sprouted from the earth, and are 
yet extremely tender. ‘They also attack the finest, and espe- 
cially the most succulent fruits, as they approach to maturity, 
and so produce their destruction, either of themselves, or by 
facilitating the destructive operation of other frugivorous 
animals, such as wasps and hornets, or that of rain, by which 
