ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



135 



demonstration (where the heat is often great) than for any other 

 purpose. 



Fig. 20. 



Giles' Live-Cell.*— G. M. Giles finds that the main drawbacks of 

 most cells for the observation of living objects are that they either 

 leak or are very difScult to clean, and suggests the following form 

 (figs. 21 and 22) to obviate these defects. Take a stout ground-edged 



Fig. 21. 



glass slip, and have fitted to it two sheaths of thin brass, about 3/4 in. 

 wide. These should be made to fit closely, but not so tightly as to 

 prevent the glass slip from sliding easily through them. To the middle 



Fig. 22. 



of one end of each sheath is soldered a small brass arm (shaped as in 

 %• 22), carrying a fine screw on one arm, which, when secured in posi- 

 tion, projects about 1/4 in. beyond the end of the sheath. A piece 

 about 1^ in. long, cut off a thin glass slide, and a thick indiarubber 



* Sci.-Gossip, 1885, pp. 7-9 (2 figs.). 



