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On a Simple Growing Slide. 

 By T. Charters White, M.R.C.S., &c., President. 



{Read Septemher 24t7t, 1880.) 



As there is miicli to interest tlie microscopical observer in watch- 

 ing tlie developmental changes taking place in what are called the 

 lower forms of life, such, for instance, as the Infusoria ; and as the 

 appliances for this purpose have not satisfied me, I have brought 

 this evening a Growing Slide that is simple, easily constructed, and 

 the use of which will enable the observer to keep his subject in the 

 field ready for daily or even hourly observation. Most of the grow- 

 ing slides with which we are familiar, are made upon such princij)lcs 

 that their removal from the microscope is necessary, and, therefore, 

 when next placed under it the special subject of observation is not 

 easily found ; but this growing slide contains its own fluid, and may 

 be left under the microscope for an indefinite period, and the obser- 

 vations and notes made of every cliange occurring from day to day ; 

 and though tlie idea is carried out roughly, I bring it more as a 

 suggestion for others to work upon and improve, rather tlian as a 

 perfectly devised contrivance. Its construction is simple ; the sides, 

 which may be of any dimensions for which you can get thin glass 

 covers, are constructed out of the strips of tliick phite glass which 

 you can get from any glass-merchant's warehouse, and whicli have 

 been cut off to reduce large plates to the required size for frames, 

 and these are virtually waste pieces, and for a few pence may be 

 procured in any quantity ; having built up a cell with these, to a 

 suitable and convenient size, then cement a piece of the same plate- 

 glass in the centre of the cell with Canada balsam ; you have now a 

 water-tight cell, having a table of plate-glass in the centre, the 

 space round which you may fill half up with water. Placing your 

 Infusoria or whatever your subject may be, on this table in Avater, 

 you cover it with the thin glass, and the water in the trough will 

 keep up any loss by evaporation witliout any saturation of the table. 

 The only drawback to this growing slide is, tliat it must always be 

 used with the microscope in a vertical position, but as observations 



