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Modern Microscopy 



commercial glass troughs unfortunately do not meet these 

 requirements. They are difficult to clean, they are in- 

 variably hard to mend when broken, and they very often 

 leak when water is put in. The one that we have found 

 most serviceable is the Botterill's trough, as shown in 

 Fig. 47, which consists of two vulcanite plates between 

 which are placed slips of glass, which are separated by an 

 india-rubber band, small bolts and screws passing through 

 the whole to hold them together. This is not an ideal 

 trough, but it certainly answers its purpose as well as any 

 at present made. 



Live-cages. — These are not used so largely for water 

 objects as for insects, etc. They consist of a brass plate 



Fig. 47. — Bottbkill's Trough. 



having a glass base-plate, over which a cap slides, having a 

 very thin cover-glass. The subject to be viewed is placed 

 between these two glasses and held firmly by compression. 

 The best form is that designed by Mr. Eousselet, shown in 

 Fig. 48, with which a condenser may be used conveniently. 

 It is also so arranged that even if a specimen be fixed at 

 the extreme edge of the glass plate, there is room for an 

 objective to work on it. The ordinary live-cages are usually 

 provided with a cover-glass too small in diameter for this to 

 be done. A very good plan is often adopted by amateurs 

 for viewing live objects as follows : A square, flat piece of 

 glass is obtained, and on this an india-rubber ring is laid, 

 into which the animalcule can be placed ; a thin piece of 

 glass is now put over the top of the india-rubber ring, and 

 this really makes a very serviceable trough. 



