258 MEMORANDA. 
other delicate fresh-water Algz in my glycerine jelly, that the 
glycerine, although it preserves the beautiful green colour, 
contracts and alters the position of the endochrome,-—to 
remedy this evil I propose, énstead of six fluid drachms of pure 
glycerine, to add to each fluid ounce of the clarified gelatine 
six fluid drachms of a mixture composed of one part of 
gelatine to two parts of camphor water, as recommended by 
Dr. Carpenter, at p. 245 of ‘The Microscope’ (1856).—Joun 
Wiriiam Lawrancz, Peterborough. 
On a Method of Preparing and Mounting Hard Tissues for the 
Microscope.*— Having for several years occupied my leisure 
moments with what are usually denominated “ microscopical 
studies,’ I beg leave to offer, as the result of successful ex- 
perience, a simple and certain method of preparing and 
mounting hard tissues, such as bone, teeth, shells, fossilized 
wood, &ce. 
I am aware that treatises upon the microscope give a few 
indications for the making of sections and embalming them in 
Canada balsam ; but they are unsatisfactory either by reason 
of their brevity or their want of precision. Specimens may be 
procured ready-made from the hands of Topping, Bourgogne, 
and others, but while they are expensive, persons in remote 
situations are obliged to purchase by catalogue without the 
opportunity of selection. Besides, it is oftentimes difficult 
or else impossible to obtain series of particular objects, so 
that the student must either limit his researches or “ pre- 
pare” for himself; in the latter case he may increase his 
number of objects indefinitely, and supply himself with many 
such as are not attainable from abroad, and divided in any 
direction he may require. 
A microscopic section should be as thin as the structure of 
the object will allow, of uniform thickness, and polished on 
both sides, whether it be mounted in the dry way or in 
balsam. To meet these requirements, I proceed as follows: 
Being provided with— 
1. A coarse and fine ’Kansas hone, kept dressed flat with 
fine emery ; 
2. A long fine Stub’s dentist’s file ; 
3. A thin dividing file and fine saw; 
4. Some Russian isinglass boiled, stvained, and mixed with 
alcohol sufficient to form a ¢olerably thick jelly when cold; 
5. A small quantity of Canada balsam ; 
6. Slides ; 
7. Cover glass ; 
* From ‘ Silliman’s Journal.’ 
