96 MICROSCOPICAL TECHNIQUE. 



transfer the insect to water with a pair of fine forceps, and wash it 

 till no more colour comes away, changing the water if necessary. 

 While the washed insect floats in clear water, slip a microscope 

 sUde under it, raise the slide, holding the insect on it with a fine 

 needle ; separate the wings from the body with a fine scalpel and 

 remove the body. With a drop or two of clear water on the slide, 

 float the wings into any desired position, keeping them flat and 

 unwrinkled, taking care to have no bubbles under them. Remove 

 any excess of water with blotting paper, and allow the wings to 

 dry. Then place a drop of thick Canada balsam near them and 

 heat the slide over a spirit or gas flame. Tilt the slide so that the 

 now liquefied balsam flows over the wings ; lower a cover-glass 

 gently into position, and allow the preparation to cool. In exami- 

 nation the veins will be found red, the depth of the colouring 

 varying with the length of time of staining, the thickness of the 

 veins, etc. The colour is well retained, so far as has been tried, 

 and successful photographs have been made. — Scietitific American. 



Improved Borax Carmine Staining Solution. -The ordinary 

 aqueous solution of borax carmine, widely employed in vegetable 

 histology, requires almost always the destruction of the cell con- 

 tents, so that only skeleton-like preparations have been hitherto 

 produced with this stain. Professor Radais obviates this objec- 

 tion, however, by the use of an alcoholic tincture, thus prepared : 

 Powdered carmine, 2 parts ; borax, 8 parts ; alcohol, 70 per cent., 

 by volume 200 parts. This mixture is placed in a flask fitted to 

 an upright condenser and heated on the water, so that the alcohol 

 boils for twenty minutes. The liquid is then cooled and filtered. 

 It is essential that the alcohol should be fully 70 per cent, by 

 volume, so that if an efficient condenser is not available the 

 strength should be 71 to 72 per cent, at starting. This carmine 

 solution keeps well in stoppered bottles. Sections should first be 

 macerated for a few minutes in a little 70 per cent, alcohol before 

 being introduced into the stain ; in favourable cases ten minutes 

 at least are necessary to obtain a well-stained result, but the section 

 may be left in the dye indefinitely without any fear of overstaining. 

 After withdrawing from the stain, the sections should first be 

 washed with 70 per cent, alcohol, and then dehydrated with alco- 



