152 



THE AMERICAN MONTHLY 



[August, 



from each side, will imprison the ob- 

 ject. If the damar wave does not 

 appear to travel freely, a little move- 

 ment with a needle at the edge not 

 touched by the medium, will accom- 

 plish the purpose, and the slide may 

 then be put away to dry ; but in the 

 case of starches it is not well to put 

 them into a very warm place. 



The same plan may be adopted in 

 the case of pollens, fern spores, etc., 

 and the two waves of damar will do 

 what is otherwise very difficult, keep 

 such delicate objects where we like 

 them to be, in the centre of the slide. 



At this place I may just point out, 

 that if good mounts of fungus spores, 

 such as the Puccinia, are wanted, the 

 spot of fungus should be removed 

 from the supporting leaf by means of 

 a very sharp-pointed scalpel, and then 

 the slip being breathed upon, the fun- 

 gus will adhere to the glass ; but in 

 some few cases, as in Xe?iodoc/iiis, the 

 spores are so dense, that it is not well 

 to at once add damar ; but in such a 

 case a drop of benzole, placed by 

 means of a bit of rolled paper or 

 match, by the side of the spores, will 

 quickly penetrate them ; when this 

 has nearly evaporated, a drop of da- 

 mar may be put direct upon the spores, 

 and I would then suggest that the 

 cover-glass be not put down for half 

 an hour, and it will be found that 

 when warmed and put down it will 

 not so easily move the objects, as it 

 would do if this plan was not followed. 



The next description of mounting 

 to which I would refer is one which, 

 to a beginner, is frequently a stumb- 

 ling-block. I mean glycerine jelly, 

 which is an exceedingly convenient 

 method to adopt when the object 

 would be rendered too transparent in 

 balsam or damar, or when it is unde- 

 sirable to dry it at all. 



In the preparation of the many 

 things from the vegetable kingdom, 

 as mosses, algae, cuticles, sections, etc., 

 and from the animal kingdom, as 

 many eyes and wings of insects, gas- 

 tric teeth, palates of the mollusca, it 

 is only necessary, if they are suffi- 



ciently clean and not too dark in 

 color, to put them for a few hours into 

 a mixture of methylated spirit, glycer- 

 ine, and water, about equal parts of 

 each, although exactness is not neces- 

 sary, as the mixture may be varied to 

 suit circumstances. 



When they are taken from this 

 mixture, they must be placed upon 

 the centre of the slide, and the surplus 

 liquid absorbed by blotting-paper. 

 Either of two plans may now be fol- 

 lowed with regard to the jelly — it 

 may be liquified by placing the bottle 

 in hot water, and then dropping the; 

 liquid jelly upon the slide, or, as I 

 frequently prefer, a small piece may 

 be cut from the bottle and put upon 

 the object and the slide gently warmed, 

 when the jelly will diffuse itself 

 through the object, and will be found 

 exceptionally free from the enemy, 

 " air-bubbles ; " but should there be 

 air bubbles, or not, it is of great value 

 to boil the jelly and object upon the 

 slide, but care must be used or the 

 mount may be ruined. Should the 

 boiling be decided upon, the clip 

 shoulcl bQ used, and the slide held by 

 the clip directly over, but not too close 

 to the flame of a spirit lamp ; it will 

 at first begin to bubble from the centre 

 outwards, and if the slide be now 

 carefully watched, a very perceptible 

 crack may be seen and heard, at this 

 moment, and without delay, the slide 

 must be withdrawn from the heat, and 

 placed upon a cold surface (in my 

 work a block of marble), when the 

 jelly will rapidly contract and the air 

 bubbles will be excluded. 



The jelly mounts are easily cleaned 

 from superfluous jelly, by brushing 

 with a soft tooth brush under a run- 

 ning tap, and the surface of the slide 

 being allowed to dry spontaneously, it 

 will be found that it is free from gly- 

 cerine smears, which interfere much 

 with the after-process of finishing. 



Micro-crystallization. 



Not being a student of crystalliza- 

 tion as a science, I have not to dis- 

 course on the classification or angles 



