Some objects, especially certain of those of the vegetable world, are of such a nature that suitable sections may be cut, either from the fresh or preserved specimen, without any preliminary preparation. All that is required is to hold the object firmly between the finger and thumb of the left hand, previously securing it in some kind of holder if necessary, and pare off the thinnest possible slices with a horizontal movement of the razor, both razor and object being kept very wet during the process. As the sections are cut they may be allowed to drop into a shallow vessel of water; and, the thinnest then selected for examination in water as previously described. Other objects are so soft that the cutting of sections becomes impossible without previously hardening them. Methylated spirit is a good hardening reagent, and many of the soft structures that have been preserved in this fluid, especially if it has been used undiluted, will be found sufficiently hard for cutting thin sections. Among the other hardening reagents used by microscopists may be mentioned a solution of chromic acid--one part by weight of the solid acid dissolved in from one hundred to two hundred parts of water, and a solution of bichromate of potash--one part of the bichromate to about forty parts of water. In either case the hardening of the object takes place slowly, and it should be examined from day to day until the necessary consistence has been obtained. The structures of many soft animals can never be satisfactorily hardened for section-cutting by either of the above reagents, and thus it becomes necessary either to freeze or to imbed them. In the former case the object is first soaked in gum water--a thin solution of gum arabic--and then frozen by an ether spray or by a mixture of ice and salt. The sections should be cut with a razor just as the object is beginning to thaw, and they may then be examined under a cover-glass, in a drop of the gum water. The other method is conducted as follows:--The soft object is first soaked in absolute alcohol to extract all the water it contains, and is then transferred to paraffin that has been heated just to its melting-point by standing it in warm water. After the object is thoroughly permeated with the paraffin, the whole is cooled quickly by immersion in cold water. Sections are now cut, the paraffin being sliced away with the substance it contains. These sections are placed in warm turpentine, where they are allowed to remain until the whole of the wax has dissolved, and they may then be mounted in a drop of turpentine, and covered with a cover-glass.