Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . Fig. 41. Tooth ofblue shark. Fig. 42. Section of sharks tooth. Fig. b on the dotted point of fig. 41, is that partof the tooth which is attached to the cartilaginousjaws of all the shark family; fig. 42 is a section atthe dotted point a of fig. 41; and fig. 43 is a sectionat the point at b. This shark was caught by a friendof mine only two years ago in the lied Sea. I may notice, for the benefit of learners, the methodI follow to prepare these teeth, either fossil or other-wise, for
Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . Fig. 41. Tooth ofblue shark. Fig. 42. Section of sharks tooth. Fig. b on the dotted point of fig. 41, is that partof the tooth which is attached to the cartilaginousjaws of all the shark family; fig. 42 is a section atthe dotted point a of fig. 41; and fig. 43 is a sectionat the point at b. This shark was caught by a friendof mine only two years ago in the lied Sea. I may notice, for the benefit of learners, the methodI follow to prepare these teeth, either fossil or other-wise, for the microscope, and which is simple a piece of fine smooth slate, and a dish ofwater; take the tooth and commence rubbing the flat side, keeping it under the water during the process,until you have ground it down to its centre. Be sureyou have no scratches on the fine polished surface ofthe article you are polishing; then have a clean, clearpiece of ordinary glass, and hold it over a small jet. Fig. 43. Section of shark tooth. with a little balsam on the centre of it, holding itto the flame till the balsam bubbles and boils well;remove your glass from the flame, and watch the airbubbles until they disappear; then place yourpolished side on the balsam, which very soon setshard; immerse it in the water in your dish again,and rub away upon the slate the last side, untilsufficiently thin and transparent for the fix a piece of glass on the polished section ofthe specimen in the usual way, and it is ready forinspection under your Shields. Joseph Weight, Jun. Planaria.—In Science-Gossip, for November,1867, E. T. Scott inquires whether certainanimals observed in fresh-water, the one with two,the other with four eyes, which when touchedcontract themselves into a hard lump, as a healthyleech does, and which move in the same way—arePlanaria. In reply, we beg to inform him that thePlanaria have neither suckers, nor other visiblelocomotiv
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