138 



SUMMARY OP CURRENT RESEARCHES RELATING TO 



Fig. 25. 



under the elastic rings, and then, by inserting a wedge between the 

 wooden and other slide the object can be placed as desired. 



Another very simple contrivance for placing an unmounted object 

 in any desired position is shown in fig. 23. By turning the milled 

 head the object can be moved in a direction transverse to the 

 apparatus, and by moving the other in or out, the object can be 

 moved in a longitudinal direction. The hole in the vertical tube 

 can be fitted with a cork to hold pins ; a small pair of forceps or a 

 piece of wax can be used to hold a geological specimen. 



Dunning' s Zoophyte-Cell. — All who work with the ordinary 

 zoophyte troughs know the difficulty there is in cleaning them, also 

 the risk of breakage in doing so, more especially with the very 

 shallow troughs. Mr. C. G. Dunning has designed the apparatus 



shown in figs. 24-26 to 

 Fig. 24. overcome this difficulty. 



The lower plate (fig. 

 25) is of metal, 3 in. long, 

 1^ in. wide, and about 

 1/10 in. thick, with an 

 oval perforation, the un- 

 der side being sunk out 

 as shown in the section 

 (fig. 24). In this sinking 

 is fixed, by means of 

 Canada balsam, a piece of 

 stout cover-glass, which 

 forms the bottom of the 

 cell, the sinking being 

 sufficiently deep to pre- 

 vent the thin glass from 

 actually bearing on the 

 stage when in use, or on a 

 table, or when laid down. 

 The cover (fig. 26) con- 

 sists of a thinner plate 

 of metal rather shorter 

 than the lower plate, 

 and having a correspond- 

 ing aperture. To the 

 under side of this plate is also fixed a piece of cover-glass. 



To use the apparatus it is only necessary to lay it flat and well 

 fill the cell with water, arranging the object if necessary ; then put 

 the cover on from the bottom edge by placing the notches over the 

 two pins which are inserted in the bottom plate, and gradually 

 lowering it, the superfluous water will then be got rid of, and the 

 whole should be wiped. The capillary attraction assisted by the 

 weight of the cover is sufficient to prevent any leakage, while the 

 pins prevent it from sliding down when inclined. Although, of 

 course, there is no supply of air, Vorticellse, zoophytes, &c., can be kept 

 under exhibition for more than two hours without change of water, 



