282 THE AMERICAN MONTHLY [Aug 



lot of yeast which is known to have been dried for several 

 months or even years. Determine whether it is still 

 alive, and note, if it is shown to he so, that this proves 

 that dryness is not fatal t(» yeast cells, also that life may 

 he suspended for an interval of time and then its activi- 

 ties may be resumed. Can you think of parallel cases 

 among plants: e. g., seeds and animals ? 



Appendix. — Simple Methods for Mounting in Canada 

 Balsam. — (a) Entire Objects. — Small objects or organs of 

 large objects such as hydroids, polyzoa, small Crustacea, 

 small plants, can be mounted in balsam if desired ; a sim- 

 ple method is as follows: (1) If there be any cellular 

 material present the specimen must first be preserved, a 

 convenient general method being as follows. (1) Im- 

 merse in ten times the objects bulk of saturated aque- 

 ous solution of corrosive sublimate i hour ; (2) Wash 

 in running water J hour ; (3) Transfer to 30 per cent 

 alcohol 20 minutes ; (4) Thence to 50 per cent alcohol 20 

 minutes; (5) Thence to 70 per cent alcohol 24 

 hours. This method is suitable for small objects in 

 which it is not desired to bring out the finer nuclear 

 figures. The perserved specimen should be stained as 

 follows: (1) Immerse in borax carmine (or any other 

 good stain) for 24 hours ; (2) Transfer to a clearing 

 fluid made by adding 2 parts of hydrochloric acid to 98 

 parts of 50 per cent alcohol and change so long as the 

 clearing fluid extracts any color from the specimens. 

 After staining the object must be completely de-hy- 

 drated — This is done by passing it through 70, 95 and ab- 

 solute alcohol, leaving it in each from 10 to 30 minutes 

 or even longer according to size. While in absolute al- 

 cohol it must be carefully stoppered, especially when 

 the atmosphere is very moist. After the water is 

 thoroughly removed the specimen can be placed in oil 

 of cloves or turpentine, till it becomes thoroughly trans- 



