On Mounting. 51 



With a little practice this can be done very neatly 

 without an air bubble in any part of the preparation ; it 

 requires patience, however, and it is no use to try air 

 pumps or any dodges, to remove the bubbles, as they 

 are useless ; the only thing to be done when an air 

 bubble lodges in a cavity of the section and refuses to 

 move in any way by gentle pressure, is to lift the cover 

 glass, and transfer the section to oil of cloves, and then 

 remount it. 



When several sections are to be mounted on one 

 slide, a slight pressure on each with the needle will 

 generally retain it in its position, if too much of the 

 mounting fluid is not used. 



It will often be found on examining preparations 

 after they have been mounted some little time, that 

 the fluid has evaporated and left a vacuum under the 

 cover glass ; in this case a drop of the mounting 

 fluid must be placed on the slide in contact with the 

 cover glass, and it will immediately run in and fill up 

 the empty space, provided always an egress has been 

 allowed to remain for the contained air, when this is 

 impossible from the small size of the hole at the edge 

 of the cover glass, the only thing to be done is to wait 

 until some of the material, of which the mounting fluid 

 is composed, has been dissolved by the fresh fluid. 

 Applying heat will effect it, and at the same time in 

 all probability ruin the specimen. 



Each preparation should be examined under the mi- 

 croscope and if found to be worth keeping, labelled. 

 On the label should be noted the tissue, date of its pre- 

 paration, mode of hardening and staining, thickness of 



E2 



