Collection and Mounting of Oljects. 23 



cell of glass, or of some black composition, surround- 

 ing the object, filled with some oil or fluid, and 

 covered with a thin glass ; some appear to have the 

 object merely placed on the slide and covered 

 with the thin glass; while in a great number 

 you will notice a peculiar clearness, as though they 

 were incorporated with the substance of the slide 

 itself. These three modes are known as mounting in 

 fluid, mounting dry, and mounting in Canada balsam. 

 The first mode is suitable for various soft and delicate 

 structures, which require to be kept in a moistened 

 state : it so happens that I have but seldom practised 

 it; full directions, however, occupying some pages, 

 will be found in Dr. Carpenter's and in other works. 



The best plan for mounting objects in the dry 

 method appears to be this : Take the object, for 

 instance, the insect's wing on Plate II., fig. 2, after 

 you have succeeded in spreading it with water and a 

 camel' s-hair brush on a piece of glass, and have care- 

 fully removed it when quite dry. Place it on the 

 centre of the slide, and lay over it a little square or 

 round piece of thin glass ; hold this steadily down, 

 and a,pply some thick gold-size neatly round its 

 edges. This will fix on the cover, and can be after- 

 wards neatly trimmed, and a piece of coloured paper 

 with a round hole in the centre, pasted over the slide 

 to preserve the edges of the cover from injury. The 

 reason for using gold-size, instead of paste or gum- 

 water, is that the slight moisture caused by the last- 

 mentioned cements causes a kind of fungus or mould- 

 like plant to grow on and around the object, and 



