E 72 MIDLA ND NATURALIST. 
* 
Notes on Histological Technique. * 
MOUNTING OF ALGAE. 
J. A. NIEUWLAND. 
In a personal communication from the well-known phycologist 
Professor G. S. West, of the University of Birmingham, England, I 
received an outline of a method of fixing, mounting, and preserving 
algae which, as he tells me, has not been given the attention that it 
perhaps deserves. "The fluid used serves at the same time as a kill- 
ing, fixing, preserving, and mounting medium, and for delicate 
structures like desmids and other algal forms, it is said not to be 
surpassed. It has the advantage, moreover, that it keeps the 
natural coloring of the green algae, something which the instructor 
in elementary laboratory work will appreciate better than anyone 
else. The fluid is a 2 per cent. solution of potassium acetate, just 
made blue with a small amount of copper acetate. The substance 
reduces plasmolysis of the cell contents to a minimum. The algae 
can be put into the solution and kept in it. Ifa permanent mount 
is wanted a small amount of the material is put on a rather thick 
slide and sealed with old gold-size several times after each drying. 
The mounts are permanent, but it is necessary to take great care 
in sealing, and to this end to use a thick slide. A thin slide will 
bend considerably in handling, and the sealing may be separated in 
this way from the slide, so that the preparation will dry up as the 
result. 
For some reason the fluid presents considerable difficulty with 
Vaucheria, and plasmolysis is hard to avoid. I have found that the 
best way to treat Vaucheria, especially the zoospores before or just 
after germination, when the plant is particularly delicate, is to kill 
it rapidly with 3 or 4 per cent. formalin. The formalin must be 
completely and quickly removed or the preparation will turn black 
afterward. Fixing for half an hour in the 3 per cent. formalin will 
not be injurious. Remove the formalin by repeated washing with 
water. If the Vaucheria thus treated is rapidly brought into 
glycerin to which a little thymol is added, the preparation will be 
* Reprinted from The Botanical Gazette 47 :237-238, March, 1909. 
