220 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



a strip of glass 3 in. by § in. This is held in position by a flat 

 steel spring about £ in. wide, folded like a pair of tweezers, and 

 having just strength enough to keep the slide firmly pressed against the 

 side of the test-tube. Tbe lower part of the tube should be carefully 

 and uniformly warmed, the copper strip being kept at tbe other end of 

 the tube by tilting the latter. After the warming the tube is again in- 

 clined, and the sublimation effected at as low a temperature as possible. 

 When the sublimation is completed, the copper foil and the spring are 

 removed and the tube corked. By this procedure the sublimate is de- 

 posited on a plane surface, so that it can be examined under high powers 

 and the slip preserved for future reference. 



Micrographic Fly-Cage. — Fig. 37 represents the apparatus exhibited 

 at the meeting of the Society on Feb. 20th (see p. 224), devised by 



Fig. 37. 



IVORY DISC 



Section on L»ne A A. 



Mr. G. H. J. Rogers, and made by Mr. C. Baker, for exhibiting the pro- 

 boscis of the common house-fly as an opaque object. It is large enough 

 for the blow-fly, but can be made any size. It consists of a brass cone 

 soldered to a brass plate with a hole in it, just large enough to admit 

 the head of the fly, which is surrounded by a disc of ivory, let into the 

 plate. The fly is gently pushed into the cone with a little piece of wool 

 behind it, and is ready for examination. A little treacle or honey is 

 put on the ivory disc ; the fly puts out its proboscis, which is kept flat 

 and in one position. It is very easy to focus, and does not require any 

 adjustment of the object more than an ordinary slide. The idea was 

 taken from the well-known paper disc and stage forceps, the ingenious 

 invention of Mr. Macer. 



Metallography considered as a Testing Method.* — In an article 

 with above heading Mr. Osmond illustrates (inter alia) the question of 



* Metallographist, i. (1898) pp. 5-27 (17 figs.). 



