1900J MICROSCOPICAL JOURNAL. 263 



ing-table, and the insertion of a needle will readily re- 

 lease the cover-glass. Warm as before, apply a fresh drop 

 to the centre of the hardened balsam, lift with a pair of 

 forceps, reverse quickly, and lower gently down upon the 

 slide, pressing down carefully so as to squeeze out the ex- 

 ces of balsam and to carry any air-bubbles with it. The 

 cover should now lie flat on the slide. It is better to have 

 a slight excess of balsam rather than a deficiency. In case 

 of the latter a drop must be put against the cover-glass, 

 when it will quickly run in by capillary attraction. Small 

 bubbles, other than any embedded in the object itself, 

 may be neglected, one of the advantages of Canada bal- 

 sam being the readiness with which it will absorb these. 

 There are certain objects, however, which are very dif- 

 ficult to free from larger bubbles than the balsam can ab- 

 sorb. In such cases it is advisable to again heat the mount- 

 ing-table, whilst holding the cover steadily, but not too 

 heavily, in position by pressing on its centre with the 

 handle of a dissecting-needle, until the balsam is seen to 

 boil. At once remove the lamp, but hold the cover-glass 

 steady until the balsam seems to have set again. By this 

 means, though it needs caution, the bubbles will be driven 

 clear of the cover-glass by the ebulition of the balsam. 

 Wire spring clips can be obtained for a penny each, and 

 it is advisable to slip one of these on before putting the 

 slide on one side to harden. This may take twenty-four 

 hours, or it may take a week, according to the amount of 

 balsam used or exuded. Under any circumstances it is 

 well not to hurry matters. The excess can then be re- 

 moved with a sharp knife nearly up to the cover-glass, and 

 the remainder cleaned up nicely with a rag dipped in tur- 

 pentine, methylated spirit, or benzole. — Sci. -Gossip. 



Wanted. — Microscopic preparations illustrating- the his- 

 tology of petals and sepals. Would like to get a full set for 

 John H. Lowell, Waldoboro, Maine. 



