I am convinced that this process is as yet but in its infancy, and that it is susceptible of great improvement. From the purely theoretical standpoint, the property possessed by gelatine, of combining in sufficiently cold solutions with bromide of silver in the nascent state, and falling to the bottom in a flaky condition, is exceedingly interesting. Evidently this property plays a part in the preparation of emulsion which has not until now been recognized. I do not doubt that it may be possible to effect, by a sufficiently low temperature, precipitation even from solutions rich in gelatine, if experiments in that direction were set on foot. What influence variations in temperature may have upon the subsequent sensitiveness of the emulsion, and whether the action of the ammonia and the bromide of potassium is more energetic, in the absence of the elsewhere-present nitric salts, are questions which can only be answered after thorough examination; and the parts played by the various additions of iodide or chloride of silver in this method of emulsification must likewise also be ascertained by experiment. The object of this article is to point out this rich province for research, and to induce experimenters to turn their attention to it; for it is only after the behavior of emulsion under all these conditions has been thoroughly examined that we can hope to reap the best results from the new process.--_Wochenblatt_. * * * * * TAYLOR'S FREEZING MICROTOME. This microtome presents all the advantages of any plan heretofore employed in hardening animal or vegetable tissues for section cutting, while it has many advantages over all other devices employed for the same purpose. Microscopists who are interested in the study of histology and pathology have long felt the necessity for a better method of freezing animal and vegetable tissue than has been heretofore at their command. In hardening tissues by chemical agents, the tissues are more or less distorted by the solutions used, and the process is very slow. Ether and rhigolene have been employed with some degree of success, but both are expensive, and they cannot be used in the presence of artificial light, because of danger of explosion. Another disadvantage is that two persons are required to attend to the manipulations, one to force the vapor into the freezing box, while the other uses the section-cutting knife. The moment the pumping of the ether or rhigolene ceases, the tissue operated on ceases to be frozen, so ephemeral is the degree of the cold obtained by these means. The principal advantages to be obtained by the use of this microtome are, first, great economy in the method of freezing, and, second, celerity and certainty of freezing. With an expenditure of twenty-five cents, the tissues to be operated on can be kept frozen for several hours at a time. [Illustration: FREEZING MICROTOME.]