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 animals. 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 separation, and occasions little or no alteration in the material. Specimens are often taken from the _frog_ and the _pig_, as being amongst the best, _Goadby’s solution_ being generally used in mounting them. The muscle of insects also shows the striæ very perfectly.