80 APPENDIX. 



bulbous expansion of the size of a pea. Insert the fine 

 point of the scissors and cut it open ; the interior will be 

 found full of food in process of trituration. Empty the 

 contents of the gizzard, and wash it out well ; place it for 

 a few days in the solution of potash ; and, finally, cleanse it 

 with some warm water and a camel-hair brush. Spread it 

 out flat between slips of glass ; when dry, place it in turpen- 

 tine for a week, and afterwards mount it in balsam. 



The best specimens for displaying the horny teeth with 

 which the gizzard is furnished are obtained from crickets, 

 grasshoppers, and cockroaches. 



PALATES (Plate 6, Figs. 167, 168, 169, 170). These con- 

 sist of a narrow kind of tongue, armed with a series of 

 horny teeth, placed in regular rows. The whelk, limpet, 

 periwinkle, garden-snail, and the snails found in our cellars 

 and aquariums, are all furnished with this peculiar appara- 

 tus, which may be obtained by laying open the body with 

 the scalpel or scissors. It will generally be found curled up 

 near the head, and may be distinguished by its ribbon-like 

 appearance : patience and skill are necessary to extract it 

 from the surrounding mass. When properly cleaned, it may 

 be at once pressed flat and dried between slips of glass. 

 Many palates polarize well when mounted in balsam ; but 

 if not intended for polarization, they should be mounted in 

 a preservative fluid, composed of five grains of salt to one 

 ounce of water. 



TONGUES, PROBOSCES, MANDIBLES, AND ANTENNAE 

 (Plate 7, Figs. 189192, 194197) are amongst the most 

 beautiful objects exhibited by the Microscope. Many of 

 these, besides the ligula, possess several sharp lancets for 

 puncturing the skin of animals from whom they derive their 

 sustenance. To arrange these organs so that each part 

 may be clearly seen, requires a good deal of delicate mani- 

 pulation. It is generally more satisfactory to mount the 

 whole head of the insect. To accomplish this, it must be 

 softened by immersion in liquor potassce for some time, and 

 the interior substance got rid of by pressure. To dry it 

 flat, place it between two slips of glass, which should be held 

 together by a spring-clip ; soak it for a fortnight or longer 

 in turpentine, until it becomes transparent, and then mount 

 it in balsam. 



The head of the bee, wasp, dronefly, blowfly, and gadfly, 

 are all excellent examples of the varied structures of these 

 suctorial organs. 



EYES (Plate 7, Figs. 201, 201a, 203). The compound 



