56 A GARDEN SNAIL SHELL. 



A GABDEN SNAIL SHELL.* 



The snail is an architect whose house-work does not fall within the 

 denunciations of Professor Euskin, or Gambier-Parry. His three-storyed 

 building has no want of curvilinear hues, it is not only weatherproof 

 and waterproof, but is also ornamented with bands and mosaics, and has 

 its interior floored with enamel. Its drainage is perfect, and its 

 ventilation irreproachable — cool in the summer and no icy-draughts 

 in the winter. 



The Garden Snail, Helix aspersa, is but one of 253 species of a 

 sanitary scavenger, whose function it is to consume and assimilate 

 into living organism much superfluous and decaying vegetation, that 

 otherwise might not only offend the human nostrils but, in a state of 

 putrescent decay, would emit carbonic acid gas, and so poison the air for 

 human beings. 



The writer, one fine spring morning, had scooped up a trowel-full of 

 mould from the base of a greenhouse wall, and in so doing noticed 

 therein a dozen snail eggs, round and glistening substances, the size of 

 peas. Wishing to obtain a minuter inspection of these globules, he went 

 in-doors for a pocket-lens. Not more than ten minutes elapsed, when, 

 on looking for the "objects" for the lens, it was discovered that they 

 had evolved into living and moving snails, and had briskly commenced 

 their march of vagabondage, henceforward " eating to live and living to 

 eat." It was evident that the sunlight or sun heat in which the eggs had 

 been left was too much for their pulpy bodies and transparent envelopes, 

 and that they had simultaneously and instinctively determined to decamp 

 and search for a lee-side and a shady corner. 



Of a pale amber hue, the twelve travellers resembled twelve 

 animated beads. Their horns were very prominent, and the salivary 

 track they left behind was very slight. They did not as yet betray any 

 ornament on their shells by way of band, or motley brown. Soft to 

 the touch, they possessed a consistency greater than was expected in 

 shells only ten minutes old. Within one week they hardened and 

 darkened in hue, and an increase in marginal growth and thickening of 

 the layer or band which wound round the columella or pillar was plainly 

 evident. The activity of the little things was quite frolicsome, wandering 

 away from green lettuce leaves and nibbling only at various portions, as 

 it' their spiral confinement required extra exercise or stretching out of the 

 foot muscles. 



The snail's shell is formed in successive layers or laminas, its cal- 

 careous and earthy growth proceeding simultaneously with the growth of 

 the animal by sympathetic exudations from the secretive glands of the 

 fleshy neck of the mantle. The neck (or collar, as it is called) of the 

 snail increasing in growth daily, it is able to push the collar from time to 

 time beyond and outside its original shell margin. In these motions, 



* This paper, written at the request of the Editors, gives a popular account 

 of the formation and growth of a Garden Snail Sneli, hi aaswer to a correspondent 

 at page 53, in Vol. II. 



