40) THE MICROSCOPE. March 
use, for at that time it may be supposed to be difficult to 
obtain any thing interesting or useful. 
To the amateur, or even professional, I suggest that 
plenty of material be gathered during the warmer mouths. 
Collect a goodly quantity of insects, seeds, spores of ferns, 
lichens, fungi, pollens, leaves having beautiful scales, 
fresh water sponges, etc. If one can, it is agreeable to 
have material to exchange. 
I find it convenient to keep materials of the same kind, 
in several bottles or jars, so,if one be damaged or broken 
I am sure of having some left. 
One will find it interesting to study the different kinds 
of leaves, wood, sections of plants, bone, teeth, stone, etc. 
These, as others, require time to prepare, but what of 
that. 
Preparations and preservatives can be found in books, 
journals, ete., of which every microscopist should have a 
representative number for study and reference. 
I find a good hardener of flesh and plants to be forma- 
lin and distilled water. I usefrom 3 to 10 per cent 
formalin according to size of specimen. 
For the study of the brain, I use—Formalin 5 per 
cent (volume), distilled water 90 per cent (volume), bi- 
cromate of potash 5 per cent (weight). Thisis only the 
average; the smaller the brain, the less formalinI use. 
I let the brain remain in this solution 4 to 8 days and 
then place in 10 per cent formalin, 25 percent alcohol, 
distilled water 65 per cent. 
One must exercise a little judgment, and keep the fin- 
gers out of the solution. Keep the formalin in rather a 
cool place ina glass stoppered bottle. See that jars 
containing specimens have glass covers and fit tightly. 
Library students in Paris wear ‘‘muzzles’”’ when perus- 
ing old books in the national library, “not because there is 
fear that they will bite the old volumes, but to prevent the 
inhalation of the book microbes into their lungs.” 
