258 ENTOMOLOGICAL NEWS. [June, '09 



prepare them for xylol in which they are cleared, and after 

 a few minutes are mounted in Canada balsam. It is conveni- 

 ent to support the cover glass on wax feet, which are made 

 by -mixing beeswax with a little balsam and lampblack. In 

 this way a specimen can be fixed in any desired position by 

 adjusting the cover glass. Bits of broken glass are some- 

 times used instead of wax feet,, but they are not so desirable 

 because they do not yield to pressure. If the specimens are 

 not pricked, or if they are cleared in anything containing car- 

 bolic acid, they are liable to shrink badly. If thorough de- 

 hydration is not secured, the specimens will collapse com- 

 pletely and turn whitish. Material properly dehydrated and 

 cleared will become still clearer in time. Too much clearness 

 is a disadvantage, since a certain opacity is more easily 

 studied. To avoid this it is advisable to pass the pricked 

 specimens from 70 per cent, to water, then stain several 

 hours in alum cochineal, dehydrate gradually, clear and mount 

 in balsam. Such specimens are opaque enough, and more or 

 less of the internal structure can be traced. Or, if preferred, 

 they can be stained directly from 70 per cent, in Grenadier's 

 borax carmine. Unstained mounts can be made without 

 clearing by passing pricked specimens from 70 per cent, alco- 

 hol to water and mounting in Farrant's medium. This me- 

 dium becomes hard much quicker than balsam, but has the dis- 

 advantage of holding bubbles permanently. It does not re- 

 quire sealing. These mounts are clear enough for many pur- 

 poses and will never become too clear. If the procedure is 

 properly carried out, they will not shrink. 



Pure gylcerin is a good medium for making temporary 

 mounts from water. If pricked aphids are mounted from 

 water in glycerin jelly and the cover glass is completely 

 sealed with shellac, they will last a long time. This medium 

 is rarely used now by histologists except for temporary 

 mounts, as the objects are likely to be disappointing after a 

 time and sealing is troublesome. 



A very common method of mounting aphids is to put them 

 fresh in balsam without dehydration. Although this has 



