ND 
THe MIcROSCcOPE. 325 
fluid was clear and the sediment scanty. The cells were clear 
and large, but in twenty per cent. they were small and 
wrinkled within, and the sediment was more scanty. The latter 
percentage plainly does not kill at once, but is certainly unfavor- 
able to the work of the yeast. 
I have cited these results because they show what is a possi- 
ble and very instructive, and what proved a very entertaining 
and enjoyable series of experiments in physiology. They are 
not beyond the powers of elementary students, yet they illus- 
trate methods of research in general use. They can easily be 
performed by any student even if he have not a microscope, 
though better if he have one. 
A NEW METHOD FOR FIXING SECTIONS. 
W. M. GRAY, M. D., 
MICROSCOPIST TO THE ARMY MEDICAL MUSEUM, WASHINGTON, D. C. 
HE following method is identical in its procedure with the 
“Gum Arabic Process,” provided the tissue from which the 
sections are cut has been successfully stained in mass. 
The advantage of the present method over the gum process is 
apparent when it becomes necessary to stain sections in aqueous 
solutions on the slide. The process is as follows. Dissolve one 
part of gold-label gelatine in one hundred parts of warm dis- 
tilled water; after the gelatine has dissolved, filter and add a 
crystal of thymol to prevent the formation of fungi. If on 
standing, the gelatine coagulates, warm slightly and use the fixa- 
tive in the same manner as the gum Arabic solution, or, in 
other words, flow a small quantity on the perfectly clean slide, 
place the object on the fluid, and heat gently until the sections 
or series of sections are flat and free from wrinkles, taking special 
care not to melt the paraffin surrounding the preparations. As 
they are perfectly flat, drain off the superabundant fluid and 
stand the slide on end to dry. The best results. are obtained if 
the slide is allowed to stand over night to dry spontaneously. 
After the sections are dry the whole is immersed in turpentine 
or other solvent to remove the paraffin, then into alcohol to re- 
move the turpentine, thence into a two per cent. solution of 
potassium bichromate for five minutes, which renders the gela- 
tine fixative insoluble. After washing the slide in water to free 
the section from the bichromate (which, by the way, will not 
