The microscope and its revelations Volume 2
William Benjamin Carpenter
Paperback
(RareBooksClub.com, March 6, 2012)
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1883 Excerpt: ...a large strong horny plate, against which the flat end of the tongue can work. On the other hand, the flattened portion of the palate of Buccinum (whelk) and its allies is used by these animals as a file, with which they bore holes through the shells of the Mollusks that serve as their prey; this they are enabled to effect by everting that part of the probosis-shaped mouth whose floor is formed by the flattened part of the tube, which is thus brought to the exterior, and by giving a kind of sawing-motion to the organ by means of the alternate action of two pairs of muscles,--a protractor, and a retractor,--which put-forth and draw-back a pair of cartilages whereon the tongue is supported, and also elevate and depress its teeth. Of the use of the long blind tubular part of the palate in these Gasteropods, however, scarcely any probable guess can be made; unless it be a sort of ' cavity of reserve,' from which a new toothed surface may be continually supplied as the old one is worn-away, somewhat as the front teeth of the Rodents are constantly being regenerated from the surface of the pulps which occupy their hollow conical bases, as fast as they are rubbed-down at their edges. 1 " Annals of Natural History," Ser. 2, Vol. x. (1852), p. 413. 579. The preparation of these Palates for the Microscope can, of course, be only accomplished by carefully dissecting them from their attachments within the head; and it will be also necessary to remove the membrane that forms the sheath of the tube, when this is thick enough to interfere with its transparence. The tube itself should be slit up with a pair of fine scissors through its entire length; and should be so opened out, that its expanded surface may be a continuation of that which forms the floor of the ...