BOTANICAL GAZETTE. 



Vol. IV. SEPTEMBER, 1879. No. 9. 



Staining and Double Staining of Vegetable Tissues. — The increas- 

 ed attention given to vegetable histology, which is largely due to the 

 cheapness of good microscopes, makes this a proper time to call attention 

 to the recent improved modes of permanently mounting objects tor study. 

 Besides this the clinical microscopes now in use enable a lecturer to pass 

 to his class the objects upon which he may be discoursing, with the dif- 

 ferent forms of tissue either in contrasting color or in different shades of 

 the same color. 



It is simply historic justice to say that thus far Americans have been most 

 successful in the preparation of these stained objects, and to none is more 

 credit due than to Dr. J. G. Hunt, of Philadelphia, and to the late Dr. Geo. 

 D. Beatty, of Baltimore. 



For convenience sake, we may divide the objects to be mounted into those 

 which should first be bleached, and those which do not require such treat- 

 ment. 



Taking up the first class we may say it is such objects as are thicker 

 than ordinary, or are of denser texture. Prominent among them we may 

 name leaves and fronds, 7vhe?i they are not cut in thin sections, but are in- 

 tended to be looked at through from surface to surface. As a rule such objects 

 are belter if they do not exceed half an inch in size; though one may suc- 

 ceed in bleaching much larger specimens, but it requires so long an im- 

 mersion in the bleaching fluid that the texture of the plant is apt to be 

 largely disintegrated, and consequently altered from its normal condition. I 

 have now before me a specimen of [.he frond oi Aspknium Filix-foemina, R. Br., 

 fully 2 inches long and one-third as wide, in which the frond texture (save the 

 chlorophyll) is almost unaltered; the indusium, sporangium and spores 

 all perfect and most beautifully stained. In such specimens bleaching is ab- 

 solutely requisite. There are others in which it is simply a convenience, as 

 for example in matured wood sections, where the processes of growth are 



