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40 BOTANICAL GAZETTE. [ Feb. 
Fixing and Staining Nuclei.—The following methods have been found 
to give excellent results in the study of nuclei. The observations were 
chiefly made with the mother-cells of the spermatozoids of various ferns, 
but the nuclei of vegetative cells also gave very instructive preparations. 
In order to fix the nuclei, the prothallia were placed in aqueous solu- 
tions of chromic or picrie acid or corrosive sublimate. The chromic acid 
solution should be a1 percent. solution ; the others concentrated. In these 
solutions they should remain from one to two hours, though in the corro- 
sive sublimate solution less time is required. The chromic and picri¢ 
acid preparations must be washed in several waters before staining. It 
has been found a good plan to leave them over night in abundant fresh 
water before the final washing. 
The sublimate preparations may be transferred to absolute alcohol, 
in which they should remain several hours. : 
The specimens are now ready for staining. The best results were 
obtained with hematoxylin and gold chloride. The secret of good heema- 
toxylin staining is to use a very dilute solution—three or four drops of 
the prepared solution in a watch-glass full of distilled water—and to allow 
the specimens to remain in this for at least twenty-four hours. Stras- 
burger is especially emphatic upon these points. 
After taking the specimens from the hematoxylin solution, they” 
must be passed successively through 50 per cent., 70 per cent. and abso- 
lute alcohol before movnting. Half an hour is usually sufficient for each 
of the alcohols. For immediate examination they may be mounted in 
glycerine, but for permanent preparations first in origanum oil, and then 
transferred to Canada balsam (dissolved in chloroform). 
The gold chloride method is simpler, and I have found it to answer 
admirably for specimens fixed in picrie or chromic acid; but with those 
fixed with corrosive sublimate or alcohol it has not answered so well. 
A Useful Artificial Light.—The following apparatus, recommended 
by Strasburger, has been found very useful in dark weather, and of course 
can be used at night: A glass globe about six inchesin diameter is filled 
ne very dilute solution of ammoniated copper oxide, and suspended 
tween a large Argand burner (gas or oil) and the microscope 
