272 The Microscope. 



few minutes, wash in 60 per cent, alcohol, dehydrate in absolute 

 alcohol, clear in oil of cedar, mount in balsam. 



Methyl green : Water solution, 2^ per cent. Nucleus, nerves, 

 amyloid substance (degenerated tissue violet, normal green). 

 Stains in 24 hours. 



Safranin : 1. Safranin, 1 part; absolute alcohol, 100 parts; 

 water, 200 parts. 2. Water, 1 part; alcohol, 1 part; safranin, 

 as much as will dissolve. For nucleus ; washed sections stain in 

 a few minutes ; wash and dehydrate in absolute alcohol, mount 

 in dammar or bals:^m. Water solution (1-1200) for bone devel- 

 opment (bone, connective tissue, red ; cartilage, 3'ellow). Wash 

 with water slightly acid with acetic acid. 



NOTES ON TnE MICROSCOPE STAND AND ON SOME 

 OF ITS ACCESSORIES. 



AN AMATEUR. 



XX. 



THIN GLASS — CONTINUED. 



The gla-s varies in thickness from one-fiftieth to one two-hun- 

 dredth inch or less, and is designated by number, the thickest 

 bearing the highest. No. 1 varies from one one-hundred-and- 

 liftieth to one two-hundredth inch in thickness ; No. 2 from one 

 one-hundredth to one one-hundred and fiftieth, and No. 3 from 

 one fiftieth to one one-hundredth inch, the price increasing as 

 the thickness diminishes. The thickest, or No. 3, is seldom 

 used for anything but opaque objects to be studied with low 

 powers. I should advise the reader not to use it for any pur- 

 pose unless it be to make cells. For covers it would better be 

 avoided. Objects covered with No. 1 glass ma^' be examined as 

 well b}' low as by high powers, and thus subserve a double pur- 

 pose. The thinner is the more difficult to use and to clean, but 

 it is better to employ it than to find the objective hampered in 

 its action because the preparator supposed that no part of the 

 specimen was worth examining with a higher power than the 

 one-inch. Another advantage in the use of the thinnest glass 

 is that it less injuriously affects the optical performance of the 

 objective. 



