NOTES AND MEMORANDA. 



Cement for Mounting Objects in Cells containing Fluid. — As 

 I have found great convenience in the use of the material I 

 am about to mention, I have thought others might find 

 it equally convenient when they have occasion to enclose 

 objects either microscopic or others in glass cells. The ad- 

 vantage it possesses arises chiefly from the circumstance that 

 it can be used under water, or weak spirit, so that the cover 

 can be affixed beneath the surface of the fluid ; and thus the 

 admission of air-bubbles can be effectually prevented. It 

 has also the advantage of retaining its adhesive property for 

 several days if requisite. 



The preparation, which may be termed " caoutchouc size," 

 is prepared by melting pieces of caoutchouc in an iron or 

 porcelain cup until it is reduced to the condition of a very- 

 viscid tar. As this tar, however, in its primitive state is too 

 viscid for use, it should be dissolved in benzine so as to form 

 a fluid of the consistence of thick gold size. 



When spread over the edges of the glass cell or vessel in- 

 tended to contain the object, it should be allowed to dry for 

 a quarter or half an hour, by which time the benzine will 

 have evaporated, leaving the surface exceedingly sticky ; and 

 this stickiness is not impaired, by immersion in water. Con- 

 sequently, if the cell or vessel with its contents is wholly 

 immersed, the cover may be applied and pressed firmly in its 

 place while still under the surface of the fluid. 



No other fastening is absolutely required, but it is better 

 when the surfaces are dry to apply a solution of shellac or 

 other varnish round the edge of the cover. — George Busk. 



Mode of Staining Animal Tissues of a permanent Purple-grey 

 Colour. — Having from time to time been very successful in 

 staining some animal tissues of a rich transparent permanent 

 purple-grey colour, it may be of use to some of your readers 

 were they acquainted with the particulars of this staining 

 process which is a very simple one, and are as follows : 



