1024 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



(3) Illuminatiiig' and other Apparatus. 



Borden's Electrical Constant-temperattire Apparatus.* — Eeferring to 

 this apparatus described ante, p. 810, Dr. W. C. Borden writes that, owing 

 to some mistake, the latter part of the description of the regulating 

 thermometer was not clear. After describing the regulating thermometer 

 made from a glass tube and small vial, and filled with 95 per cent, alcohol 

 and mercury, which will keep the temperature within one-half a degree, it 

 was intended to say that a simpler one, which will keep the temperature 



within two degrees, can be 

 Fig. 2-i2. made by simply blowing a bulb 



on a glass tube and filling the 

 bulb and a portion of the tube 

 with mercury alone. 



Frog-holder, f — Mr. W. 



Fearnley describes the frog- 

 holder, fig. 242, which he re- 

 commends, as enabling the 

 frog to be placed " in a com- 

 fortable position." 



It consists of a piece of 

 cardboard 13 x 8 cm., bent at 

 right angles across its larger 

 axis, the angle being main- 

 tained by two copper rectangu- 

 lar straps riveted to the card- 

 board. A rectangular piece is cut out of the middle of the horizontal half 

 and a glass slip put in between the cardboard and the copper straps. Two 

 slits in the upright half, 1 cm. apart, admit a length (12 cm.) of broad tape. 

 " The frog sits quietly for half an hour at a time upon this contrivance 

 with or without whiffe of chloroform," 



Macer's Insect-holder. — This (fig. 243) has been designed by Mr. E. 

 Macer for showing the head, eyes, proboscis, &c., of insects in their living 

 state, with their mode of taking food. 



The cones are made of pieces of writing-paper gummed together, 

 and left to dry. Some small discs about 5/16 in. in diameter 

 are cut, and a hole made in the centre with a No. 3 or 4 

 saddler's punch. These are blacked and gummed on the cone 

 near to the apex, and, when dry, the apex is cut off level with 

 the disc. With a small stiletto the hole should be made round 

 and smooth. It is necessary to make the holes of different sizes, 

 viz. Nos. 11, 12, 13, 14, 15, and 16 B.W. gauge, to suit the 

 various- sized insects. The disc on the top of the cone is to 

 lay a piece of honey on, to tempt the insect to extend its pro- 

 boscis in order to show the act of sucking. 



For catching the fly, glass tubes, 2^ in. long by 1/2 in. in 

 diameter, with corks to fit, are useful, having a V groove cut 

 in the cork in order to let air into the tube. At the other end of the tube 

 is placed a small plug of cotton-wool. To pass the fly into the cone, hold 

 the tube upright, shake the fly to the bottom (the wool being at the bottom), 

 draw the cork, and place the base of the cone on the tube ; then hold the 

 apex of the cone to a bright light, and gently push the plug of wool up 



Fig. 243. 



* Amer. Mod. Micr. Journ., viii. (1887) p. 175. 



t ' A Course of Elementary Practical Histology,' 1887, pp. 194-5 (1 



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