191 



On Mounting in Glycerine, and on Making Cells of Thin 



Glass. 



By Dr. H. T. Whittell, M.D., F.R.M.S. 



(Bead December 22, 1882.) 



The working microscopist frequently meets with objects which 

 he would gladly preserve, but which, having been prepared only 

 for immediate observation, and lying under the cover-glass floating 

 in a drop of water or glycerine, with a quantity of the same fluid on 

 the slide outside the cover, are not easily surrounded with a coating 

 of impervious cement, so as to be secured as permanent preparations. 

 If the worker attempt to raise the cover, and to remove the pre- 

 paration to a ringed slide, he is almost sure to lose his object, or 

 so to disarrange it that it is of no further use. If he apply pres- 

 sure to hold on the cover while he cleans away the superfluous 

 liquid, he produces a sort of microscopical squash, much delighted 

 in by dealers in insect preparations, but which is spoiled for all in- 

 structive uses. 



Glycerine can always be floated under preparations of this kind, 

 by the usual plan of applying bibulous paper on one side of the 

 cover and a drop of glycerine on the other ; but however carefully 

 this be managed, the uncovered part of the slide becomes more or 

 less smeared with the glycerine, which it is extremely difficult or 

 impossible to remove, so as to get a good adhering surface for the 

 cements usually employed for securing a permanent mount. It is, 

 of course, easy enough to mount in glycerine when a preparation is 

 placed on a ringed slide and the cover-glass has been edged with 

 cement, or even when a preparation can be placed so that just suffi- 

 cient glycerine can be applied to run to the edge of the cover and 

 no farther ; but in the every-day student life of real work these 

 precautions cannot be taken, and what is wanted is an effective 

 plan for removing superfluous liquid and binding down a cover- 

 glass over an object in the exact condition in which it has been 

 found. During many years I have tried all the plans and cements 

 that in the course of my reading I have found recommended. Now 



