174 Modern Microscopy 



sacs with a pair of forceps, and place the pollen in a bottle 

 of turpentine ; soak for several days to remove all trace of 

 air, then pour off the turpentine ; take up a little of the 

 pollen on the point of a penknife, and place it in a few 

 drops of Canada balsam on a cover-glass ; stir up with a 

 needle to spread the grains evenly over the cover, and put 

 away to dry. When the balsam has dried, add a few more 

 drops of balsam, take up the cover with a pair of forceps, 

 and mount it on a warm slide. This method of mounting 

 must always be employed for pollens, because, if they 

 are put up in any other way, the balsam only hardens at 

 the edge of the cover, and remains in a more or less fluid 

 state in the centre, with the result that, if the slide were 

 placed on its edge, the specimens would run together in a 

 heap at the lower side of the cover. 



Pollens may also be mounted as opaque objects ; see 

 Lesson XIII. on Dry Mounts. 



Pollens may also be stained various colours by aniline 

 dyes. Place some fresh pollen in methylated spirit, and 

 soak until air and most of the colour is removed. Then 

 pour off the spirit and add a strong alcoholic solution of 

 some aniline dye of the desired colour ; any will do so long 

 as it is soluble in alcohol. Soak in the dye for an hour or 

 two, then pour off the stain, just rinse in spirit, pour this 

 away, and add clove-oil, and when clear pour off the oil ; 

 take up a little pollen on the point of a knife, and mount 

 in Canada balsam as directed for unstained specimens. 



Specimens of pollens are sometimes stained many colours 

 on the same slide. This is done in the following way : 

 Take some pollen and divide it into equal quantities, each 

 one of which is to be stained in a different dye. Then when 

 they have been cleared by the clove-oil they are all mixed 

 together and mounted in balsam. 



Pharmacological Specimens. — Students of pharmacy 

 may desire to make sections of the dried stems, roots and 

 leaves with which they deal. Place the dry specimen in 

 water, and soak until it resumes as nearly as possible its 



