The advantages of some contrivances for facilitating the examination of objects from time without disturbance, and which could be kept as nearly as possible under the same conditions under which they were first observed, has at all times been a desideratum in microscopic science ; and the pages of the ‘Microscopical Journal ‘have been usefully occupied in making known several valuable aids for this purpose ; and as the growing stage lately brought under the notice of the Dublin Microscopical Club appears to present some advantages over growing slides at present in use, I have been induced to furnish a more ample description of’ it with an illustrative diagram. To my view, a growing stage or slide should possess the following qualities :—1. It should be efficient, and not likely to go out of order, neither flooding the object and overflowing the “stage, or drying up and allowing the air to get under the cover ; (2) it should be easily cleaned; (3) it should work well for at least a week, and even then should be capable of being suppled with fresh water without disturbing the object ; (4) it should enable the investigator when, in ordinary microscopic examination with a common slide and cover, he may have found something which he may wish to preserve moist, and observe at on a future occasion to do so with facility; (5) it should allow of the object being examined at any time without displacement ; (6) it should permit the whole of the covering glass to be examined, and it should not be in the way of any other piece of apparatus ; and lastly, it should not be costly in price. Now, all these objects seem to me to be secured in the growing stage under consideration. The appliance would appear to be peculiarly valuable to those who would wish to watch the varying changes in microscopic algæ, rhizopods, infusoria, rotifera, or anything requiring to be kept moist while under investigation. The microscopist, in his usual investigations with an ordinary slide three inches by one inch, and with a common covering glass, frequently sees objects which he would wish to keep under notice for several hours, perhaps days or weeks, and this he will be enabled to accomplish by merely placing the slide on this stage, and at any time transferring it again to the stage of the microscope, or by putting the growing stage, with slide upon it, on the stage of the microscope, the whole of the covering glass can be brought under inspection, so that no object which had been under the covering glass can escape observation. I have several rhizopods under notice at present for upwards of a week ; and I have kept rotifera healthy for days in this appliance. The construction of this stage is so simple as to admit of any one expert in cutting glass to make it in a few hours ; and I have drawn a diagram, to scale which will facilitate its construction.

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