COLLECTION OP SPECIMENS 167 



tion under the dissecting-microscope, for the pur- 

 pose of detecting any lingering air-hubbies or 

 traces of soil. Some of the leaves are carefully 

 dissected away (where necessary, both from stem 

 and branch), and are placed in a small heap by 

 themselves, together with any other part of the 

 plant that may be desired, such as the capsule, 

 peristome teeth, etc., being also kept moist. The 

 glass slip to be used in the mount is next placed 

 upon the flat tin cover of the hot-water bath, and 

 a small pool of the liquid jelly is put upon it by 

 means of a glass pipette, ready for the reception 

 of the specimen, which, after being freed from 

 as much of the preparatory fluid as is possible, 

 without the risk of allowing air to make its way 

 back among the leaves (either by tilting the glass 

 slip on which the specimen has been temporarily 

 placed, or by a judicious use of blotting-paper), 

 is gently lowered into the jelly. While the jelly 

 remains liquid all remaining air-bubbles must be 

 carefully removed with the dissecting-needles, 

 and here the binocular dissecting-microscope will 

 be found invaluable. This operation is often par- 

 ticularly irksome, but it should be remembered 

 that the success of the slide entirely depends upon 

 the care with which it is carried out ; for nothing 

 detracts more from the appearance, and only too 

 often from the value of a mount, than the 

 presence of these disfiguring silvery globes of air, 

 lurking among the interlacing leaves, or, perhaps, 



