MOUNTING AND PKEPAKATION OF OBJECTS. 55 



paration, the specimen is placed on a square of thin 

 glass, (which may be fastened to an ordinary wooden 

 slip or not, we prefer not), and covered after the 

 application of a suitable medium with another 

 square of the same size, both if not fastened by the 

 medium itself are cemented by passing a brush 

 charged with any of the usual varnishes round their 

 edges. When dry they are either permanently in- 

 serted in a boxwood slip A, fig. 23, or what is much 

 more convenient, placed when required for examina- 

 tion within or on one, by any of the methods shown 

 in the figure being adopted. 



The advantages claimed for this plan are, con- 

 venience of storage, postal transmission, etc. ; possi- 

 bility of examining both sides of the specimen ; a 

 high power objective sustains no injury if it happens 

 to be driven through the preparation ; the aberra- 

 tions caused by the thickness of the glass slides 

 usually employed, are removed; when using high 

 powers the condenser can be brought close to the 

 object. The examination of objects with oblique 

 light is facilitated, and their definition wonderfully 

 improved ; and even with direct light, markings can 

 be seen which defy resolution, if the object be 

 mounted in the usual way; and finally one slip alone 

 is necessary for the reception of any preparation re- 

 quiring examination. 



Many objects, among which may be mentioned, 

 scales of moths and butterflies, etc., require no 

 previous preparation, all that is necessary after 

 placing them between thin glass, is to pass a 



