169 



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NOTE ON A MODIFICATION OF THE ROUSSELET 



LIVE-BOX. 



By. A. A. C. Eliot Merlin, F.R.M.S. 



(Bead November l$th, 1904.) 



I venture to draw attention to a slight modification in the 

 construction of Mr. Rousselet's very admirable live-box that 

 has been found useful for the continuous observation, under 

 high powers, of living monad and bacterial forms. 



As usually made, the appliance is perfectly adapted to the 

 purpose for which it was designed — namely, the critical examina- 

 tion of animalcules in general ; but when employed for studying 

 the smaller kinds of monads and bacteria existing in infusions of 



Mr 



decaying matter, it is found in practice that the rapid evaporation 

 of the water-film frequently cuts short the observation of some 

 particularly interesting organism, which it would have been 

 desirable to keep in view for a longer period. 



In order to retard evaporation, the large cover-glass should be 

 cemented to the carrier, instead of being held loosely hi it by the 

 screw arrangement, which is intended to facilitate the replacing 

 of a fractured cover. The carrier can easily be constructed with 

 a broad flange to facilitate this, and in the event of breakage, 

 no practical microscopist would experience any difficulty in fixing 

 another cover. 



In addition to the cemented cover-glass, it is only necessary 

 that the carrier should accurately fit into the box in such a 

 manner that an elastic band may be placed round the rim of 

 the whole, over the line of juncture, thus rendering the appliance 

 practically air-tight. 



