পাতা:পদার্থবিদ্যাসার.djvu/১৪৫

134 well distinguish what they were to avoid, or what they might approach. To prevent this inconvenience, they are furnished with what we may term telescopic eyes. Those which children call the suaii’s horns, are four tubes, with a glass at the extreunity of each ; or if you will, you inay call them four optic nerves, which end in as many beautiful eyes. These the suail can elevate, and turn about in every direction, and lengthen or contract them, as we do the telescope. Pup. I do noi perceive ihat they have amy feet. Tut. To show the diversity of the divine works, they have two large muscular skins instead of feet, which they can lengthen and contract at pleasure, by. which means they move and draw their castle, which rests upon their backs. And to prevent accidents, they are provided with a viscous humour, which, by its cohesion, secules them fron sailing, and renders them impenetrable to moisture, by au siły natter, with which they close oil the pores of their skis, Pup. And uow please to iufornu me liwv tiyis sheli is made. Tut. The snail has a very small, soft shell, when she leaves the egg: this sluell forms the basis of a second, which is gradually increasing. . The first is the centre of the otiter, and the whole is formed by adding new circles to the first shell. And as her body can only be extended towards the aperture, this must consequently be the part which receives the fresh accessions. The materials from which the shell is made, are lodged in the body of the animal, and formed by a viscous flaid, and sandy particles of exquisite fineness, which thicken into a consistence round the extremity