14 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



immediately follows the failui-e of this power, and is preceded by the 

 drying np of the skin. All the species are extremely voracious, and 

 devour an incredible quantity of food in a short time. Those found in 

 this country are generally supposed to be vegetable feeders, but nearly 

 all of them subsist occasionally upon dead animal matter, of which they 

 seem to be fond, and when in confinement sometimes attack and devour 

 each other. It is probable, therefore, that in their natural condition, 

 all of them at times resort to animal food, and devour earthworms, in- 

 sects, and their larvae, and such other animals as, inhabiting the same 

 retreats, are like themselves slow of motion and defenceless. It is cer- 

 tain, however, that the principal food of those species which frequent 

 the neighborhood of houses and gardens consists of the tender leaves of 

 succulent plants and of ripe fruits. Upon these, in Europe, they perpe- 

 trate serious ravages, often destroying in a night the labors and hopes 

 of the gardener, and in some years committing so much injury, and 

 interfering to such a degree with the prosperity of the agriculturist, that 

 they are ranked among the scourges of the country. Like caterpillars, 

 locusts, and rats, they are considered to be perpetual enemies, and a 

 war of extermination is carried on against them. To limit the extent 

 of the evil, many remedies have been proposed, and among others the 

 prayers and exorcisms of the church have been claimed, but without 

 any considerable abatement of it. Happily, we are not in this country 

 subject, in the same degree, to the mischief done by these animals, for 

 their excessive increase is kept in check, probably, by the vicissitudes 

 of the climate ; but it may be useful to know that a border of ashes, 

 sand, or sawdust, laid around the bed containing the plants it is desired 

 to protect, will prove an impassable barrier to the slugs, so long as these 

 substances remain dry. When the slugs attempt to pass the barrier, 

 they become entangled in the dry ashes or sand, which envelops them 

 entirely. The particles of these adhere to the viscid surface of the ani- 

 mals, who, in vain endeavoring to disengage themselves from them by 

 secreting new mucus, at length become exhausted and die. 



The growth of the slugs is remarkably rapid. We have known the 

 young to double their size and weight in a week. The earliest hatched 

 young of the season generally attain their full maturity before the end 

 of the first year, although they may afterwards increase somewhat in 

 bulk. Those which leave the egg at a later period mature during the 

 second year. Individuals kept in confinement and fully fed reach a 

 much greater size than when in their natural condition. 



