A _crochet-needle_ holder made of bone, and which may be bought at the smallware dealers’ for about sixpence, makes an admirable handle for microscopical needles. At one extremity there is a small cavity, closed with a cap, for the storage of reserve needles, whilst the other end terminates in a metal tip, provided with a crucial slit and central perforation for the reception of the needle in actual use, and so arranged that, by means of a small screw-nut, needles of various sizes may be firmly held in position. Footnote 12: If square covers be employed, they may be fixed to the slide by a simple method much in vogue in Germany. A thin wax taper is to be lighted, and being partially inverted for a few seconds, the wax surrounding the wick will become melted. After the slide has been freed from excess of glycerine, a drop of this heated wax is allowed to fall upon each corner of the cover, and a line of the melted wax run along the margins of the cover between these points, so as perfectly to surround it. If a good coat of white zinc cement be subsequently laid over the wax a very durable, and not unornamental, line of union will have been formed. [Illustration: METHOD OF APPLYING COVER.] 17. _Use of Freezing Microtome._—Our preceding consideration of the method of employing the microtome in conjunction with paraffine as an imbedding agent (§ 11), will have formed a very suitable introduction to the study of the somewhat more complicated process of imbedding the tissue in gum, for section in the freezing microtome. This method is of the utmost value to the practical histologist, for by its means he is enabled with ease to possess himself of perfect sections of several structures, the cutting of which, before the introduction of this process, was always a matter of difficulty and anxiety. The freezing microtome is especially valuable for the section of such substances as from their extreme delicacy are liable to be injured by being imbedded in paraffine—for instance, the delicate villi of the intestines becomes very frequently, by the use of paraffine, denuded of their epithelium, and the villi themselves not seldom become torn off or otherwise damaged. The great value of the method is also very well seen in the treatment of those tissues which, like the lung, are of such loose and spongy texture as to offer insufficient resistance to the knife unless their interstices have previously been filled up with some solid yet easily cut material. As the space at our command is strictly limited, we are precluded from entering as fully into this branch of section-cutting as the importance of the subject demands and our own inclination would lead us. To those who wish to become thoroughly conversant with the full value of this method we cannot do better than recommend the perusal of Professor Rutherford’s _Practical Histology_, 2d edition, than which, on