108 PREPARATION AND MOUNTING 



to a clean slip of glass, repeating the process, and at last washing 

 well, good specimens may be procured. Most of these should be 

 mounted in some of the preservative liquids in the manner described 

 in Chapter IV. Many, however, may be dried on the slide, im- 

 mersed in turpentine, and then mounted in balsam ; but liquid is 

 preferable, as it best preserves the natural appearance. Certain 

 kinds of vegetables require a different treatment to separate these 

 spiral vessels. Asparagus is composed of very hard vegetable 

 matter, and some have recommended the stems to be first boiled, 

 which will soften them to such a degree that they may easily be 

 separated. Dilute acids are also occasionally used to effect this ; 

 and in some instances to obtain the raphides caustic potash may 

 be employed ; but after any of these agents have been made use 

 of, the objects must be thoroughly cleansed with water, else the 

 dissecting instruments (and perhaps the cell) will be injured by 

 the action of the remaining portion of the softening agent. 



For the dissection of animal tissues it is necessary that the 

 instruments be in the best order as to sharpness, &c. ; and as the 

 rules to be observed must necessarily be somewhat alike in many 

 instances, the treatment required by some of the objects most 

 frequently mounted will now be described. We may here remark 

 that cartilage can be best examined by taking sections, which will 

 show the arrangement of the cells very perfectly. This, however, 

 is plainly seen in the mouse's ear without any section being 

 necessary. Glycerine, the preservative liquids before mentioned, 

 and Canada balsam are all used to mount it ; but perhaps the 

 first named may be preferred in many cases. 



MUSCLE. This is what is commonly called the " flesh " of ani- 

 mals. If a piece be laid upon the slide under the microscope, 

 bundles of " fibres " will be perceived, which with needles and a 

 little patience may be separated into portions, some of these being 

 "striated," or marked with alternate spaces of dark and light. 

 Some of the non-striated or smooth class of muscle, such as is found 

 in intestines, may be prepared for the microscope by immersing 

 for a day or two in nitric acid diluted with three or four parts of 

 water, and then separating with needles and mounting as soon as 

 possible. Sometimes 'boiling is resorted to to facilitate the sepa- 

 ration, and occasions little or no alteration in the material. Speci- 



