DISSECTION or VEGETABLE TISSUES. 353 



as the whole or any of the vessels have been sufficiently 

 cleaned, they may be placed in some fresh water, and the 

 process of dissection repeated until they are fit for mounting, 

 which should be done in fluid in a thin glass or other suitable 

 cell. When the vegetable matter is very tough, and the 

 vessels firmly aggregated together in bundles, as in the edible 

 rhubarb and asparagus, they may be easily separated after 

 boiling ; this plan will also answer very well for leaves that 

 are very thick, and from which the cuticle can only be dissected 

 with difficulty. Dilute muriatic acid may also sometimes be 

 employed as a macerating fluid, but if the parts are subse- 

 quently to be dissected, the vegetable matter should be well 

 washed before the steel instruments are used, otherwise they 

 wUl be liable to become rusty. In such plants as the rhubarb, 

 and various species of cactus, in which oxalate of lime abounds 

 in stellate crystals, termed raphides, caustic potash may be 

 employed to decompose the vegetable tissue; and, to save 

 time, the potash may be heated, and, after sundry washings in 

 boiling water, the crystals may be obtained perfectly clean. 

 The cuticle of the leaves of many plants may be very easily 

 removed after a little maceration, a small portion being 

 seized by the forceps and torn off'; much larger pieces may be 

 frequently stripped off" by means of a scalpel and the thumb, 

 the cuticle being first raised by the former, then firmly kept 

 upon the blade by the latter, and torn in the direction in 

 which it is most abundant. The cuticle of the Pelargonium 

 tribe wUl be found amongst the most beautiful. 



Animal Tissues. — For this purpose all the apparatus described 

 under the head of dissecting instruments will be required. 

 In the invertebrate series, the process resembles very much 

 that of vegetables; after having laid open the body, the various 

 parts may be separated or unravelled by means of the forceps 

 and the dissecting needles, but in the higher or vertebrate 

 series, the scissors, scalpels, and the other cutting instruments, 

 will be in frequent demand. It would be impossible in a 

 treatise like the present to give a code of rules appHcable to 

 all kinds of animals, but our remarks must be confined to those 

 most generally useful to the microscopist, as full directions for 

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