MICEOSCOPT. 835 



lilitrascopjr. 



A paper read by Mr. Thomas Bolton at a recent meeting of the 

 Birmingham Natural History Society, " On the Examination of Eotifsra 

 and Infusoria under the ilicroscope," suggests a remark or two which 

 may be useful as hints to some of our readers. 



Most forms of compressorium are useless, all are expensive. Those 

 who try the following will be surprised at the efficiency of the apparatus. 

 Two pieces of thin glass are cemented on to a glass slip in the shape of 

 the letter |_, but with the two strokes of the letter about equal in length, 

 and another thinner and longer one is fixed lougitudinall\-, thus [_ 

 The [_ serves to retain in position a square shp of cover glass placed, 

 of course, not on the [_ but inside it ; the horizontal piece, which should 

 be ground to a bevel on its top edge before fixing it, ser\-es to carry a fine 

 needle, the point of which is inserted beneath the edge of the cover glass. 

 This point being tapered, it is easy to increase or diminish the thickness 

 of a film of water carried between the cover and the shp by pushing thq 

 needle further in or out, and so to form a cheap and effective com- 

 pressorium. 



Those who possess a Ross's four-tenths condenser will find the 

 arrangement of stops marked O over B give the most perfect dark back- 

 ground illumination, available, by unscrewing the top lens of the com- 

 bination, for low powers. 



The beauty of Rotifers and Infusoria seen by this illumination is 

 immensely enhanced by feeding them with carmine, sparingly siipplied 

 to the water by drawing a camel-hair brush, charged with some of the 

 pigment, along its surface. In a few minutes the stomachs of Rotifers 

 and the cavities of Infusoria are painted w^th the most glowing colour, 

 while the ciliary cuiTents to and from the animals are traced out in 

 equally brilliant Hnes. 



The cases of all the thecated Rotifers are tinged with the colour 

 upon which their tenants are fed. Hence evidently the material out of 

 which they are constructed is a product elaborated from the food of the 

 animal. 



Microscopists will be giad to hear of a really good low priced revohnng 

 microscope table, which is accurately described in the maker's 

 advertisement as " steady and substantial." The legs, which form 

 a tripod, are handsomely cast in iron and bronzed ; the top 'is 

 made of a thick slab of slate. Without being inconveniently large it is 

 large enough for all practical purposes. The microscope and lamp may 

 be readily adjusted at one side of it, and then quietly moved round 

 without readjustment to other students sitting round the table. There 

 is room on the table for a compound microscope and lamp, a simple or 

 dissecting microscope for preparing objects for the larger one, or for 

 biological laboratorj' work, and for note-book and text-book, or other 

 writing materials, either of which may be successively brought round 

 to the student as it may be required, by the mere revolution of the 

 table. The top being made of slate is very serviceable and easily 

 cleaned. An ornamental cover over the slate top when the table is not 

 in use for microscopical work wiU make it fit for a place in the drawing 

 room. The table is also made with a soHd mahogany top, the centre of 

 which is inlaid with leather to meet the wishes of those who prefer a 

 wood to a slate top. The manufacturers are Messrs. Hassall and Singleton, 

 ironfounders, Birmingham, who have arranged with Sir. T. Bolton, 17, 

 Ann Street, Birmingham to supply retail customers. 



