Page:Natural History, Mollusca.djvu/52

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MOLLUSCA.

fluence in brightening the colour. My experiments were performed in winter, and I will not affirm that the intensity of a summer's sun would not in some degree have modified the result. There appears to me one objection to this material ever having been used to dye large surfaces of uniform colour; for from the admixture of mucus with the colouring matter, when any quantity of the latter is collected, the hue is found to imbue the cloth in a mottled or blotched manner, some parts being much darker than others. What method the ancients had of avoiding this appearance I do not know.

I have seen it repeatedly stated that the slimy liquor remaining in the shell of the common snail, when the animal is crushed, is an admirable cement for glass or china, resisting both heat and moisture. I have tried it both simple, and mixed, as sometimes directed, with quick-lime in powder, but am compelled to confess, that I found it utterly worthless, the adhesion being in every case no greater than if I had used spittle for the purpose.

Let us now see what rank the Mollusca can assume among those creatures which inflict direct injury upon man. The ravages committed by various species of snails and slugs are often annoying, and sometimes serious. There are probably few of my gentle readers who have a garden at their disposal, who have not been disappointed of their crops of spring flowers by the nightly depredations of these pests. The border has been well dug and smoothed, the seed has been carefully sown, and the spot has been eagerly watched from day to day; but no sooner have the tender seed-leaves appeared above ground in a slender green