ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 705 



After thirty minutes the eggs are washed in distilled water, passed 

 through 30 per cent, and 70 per cent, alcohol (three hours in each), 

 preserved in 90 per cent., and cut in paraffin. The sections are fixed to 

 the slide with albumen, stained with safranin, and mounted in xylol 

 balsam. 



Preparing and Mounting with Pressure Insects entire, as Trans- 

 parent Objects.* — Mr. T. W. Starr adopts the following method : — 



After procuring the insect, place it under a tumbler with a few 

 drops of ether. When dead, wet it with alcohol, and place it in liquor 

 potassae, U.S. P., and let it soak until the skin is soft, and until, on 

 slight pressure, the contents of the intestine can be pressed out through 

 the natural or, if necessary, an artificial opening. This is best done 

 under water in a white plate. 



When this is effected the object is to be cleaned. Have a camel's 

 hair brush in each hand ; with one hold the object, and with the other 

 brush every part of the insect on both sides. Float it on to a glass 

 slide, and dispose each part in a natural position, either creeping or 

 flying. Cover this with another glass slip of the same size, and press 

 gently together, using only sufficient force to make it as thin as possible 

 without crushing or destroying it. Confine the glasses, with the insect 

 between them, with a fine brass wire, and place them in clean water, to 

 remain twenty-four or thirty-six hours ; this will give the insect a posi- 

 tion that is not easily changed, and it is therefore proper that the position 

 be such as you desire when the insect is finished. Eemove the wire and 

 open the glasses carefully under water, and float the insect off; give it 

 another brushing, and let it remain a few hours to remove the potassa. 

 Transfer it to a small but suitable vessel containing the strongest alcohol 

 that can be obtained, pursuing the same course as with the water, placing 

 the specimen between glass slips tied together, and let it remain about 

 twenty-four hours. 



Transfer to a vessel containing spirits of turpentine. It is to remain 

 in this, kept between the glasses, until all the water is removed. While 

 in the spirits of turpentine the insect is to be released several times, and 

 the moisture removed from the glasses, and the insect again confined. 

 When no moisture is seen to surround the insect, heat the glass slips 

 containing the insect over a spirit-lamp until the contained turpentine 

 nearly boils, when, if any moisture is present, it will show its presence 

 when the glasses are cold. 



If free from moisture it is ready for mounting. Float it on to a suit- 

 able glass from the turpentine, drop a sufficient quantity of balsam upon 

 it, examine and see that no foreign substances are present, heat the cover 

 slightly, and apply in the usual way. After a day or two heat the slide 

 moderately, and press out the surplus balsam, and place a small weight 

 upon the cover while drying. After the lapse of a suitable time remove 

 the surplus balsam, and clean the slide. 



In all the operations the utmost cleanliness is essential. The liquids 

 should be frequently filtered and kept from dust, and a large share of 

 patience will be found necessary. 



After sufficient time has been given to allow the balsam to harden, so 

 that the cleaning will not displace the cover, remove the surplus from 

 around the cover-glass with a warm knife, and then moisten a soft tooth- 



* Queen's Micr. Bull., vi. (1889) p. 29. 



