4 The Microscope. 



in the performance of their duty; on the other hand, they guard 

 with jealous zeal the integrity of their domain ; should struc- 

 tural injury occur to any part, they are easily on the guard to 

 resist destructive processes and to furnish active aid in institut- 

 ing repairs. 



A USEFUL MOUNTING MENSTRUUM. 

 DR alfrp:d c. stokes. 



IN a recent number of Malpighla, M. Aser Poli called atten- 

 tion to the oil of cajeput as a valuable medium in which 

 to place objects before their permanent mounting in Canada 

 balsam, it being used as a clearing agent instead of the oil of 

 cloves. He states that it is soluble in dilute alcohol and thus 

 permits of the direct transfer of the object to it, thereby avoid- 

 ing the use of absolute alcohol. He also remarks that trials 

 with the oil have been followed by beautiful results, the prepar- 

 ations being perfectly clear, and that delicate objects such as the 

 marine Algffi, which are among the most difficult to preserve in 

 a satisfactory way, are, when treated with the oil of cajeput, 

 almost entirely free from the ordinary obnoxious shrinkage. 



These qualities are all excellent ones, and by the microscopist 

 that does but little work in mounting, the chance to simplify the 

 operation should be hailed with joy. To do away with one of the 

 processes that modern methods seem to consider necessary will be 

 a boon. By the use of the oil of cajeput the worker can simplify 

 his methods by discarding the absolute alcohol, and thus not 

 only save himself considerable trouble and some time, but some 

 expense, as an object cleared, or soaked in oil of cloves, can not 

 well be transferred from it to balsam without the intervention of 

 absolute alcohol. 



After having been cleared, or soaked, in the cajeput oil, the 

 object may at once be mounted in the ordinary balsam or in 

 that dissolved in benzol or in chloroform. It is this character 

 that gives the oil its chit f value. Absolute alcohol must be kept 

 in a specially prepared bottle, as it evaporates rapidl}' and ab- 

 sorbs water greedily. To avoid its use is pleasant indeed. 



Since reading M. Poll's account of the action of the oil I have 

 been making a few experiments, and refer to them here in the 

 hope that some that in their microscopical work have more need 



