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Staining. VII. Iron alum, 4 percent, 24 hrs. 
VIII. Rinse in distilled water. 
IX. Alizarine sodium sulphonate, 24 hrs. 
(i to several cc, saturated alcoholic solution, in 80 to 
100 cc. distilled water.) 
X. Heat in crystal violet, 3 to 5 min. after vapor rises. 
(3 percent alcoholic solution crystal violet and aniline 
water, equal parts.) 
XI. Rinse in distilled water. 
XII. Destain in 15 percent acetic acid. 
XIII. Wash in running water, 5 to 10 min. 
XIV. Dry with filter paper. Dip in absolute alcohol. 
XV. Bergamot oil, followed by xylol. 
This stain gave a very beautiful result, the mitochondria being colored 
a dark violet or blue, with a background of old rose. Only in exceptional 
cases was the background too light to be satisfactory. 
Regaud's method of fixing and staining was also employed, to some 
extent, upon the plant tissues. 
Fixation. I. Bichromate of potassium, 3 percent, 80 vols., and com- 
mercial formalin, 20 vols., four days. 
II. Bichromate of potassium, 3 percent, eight days. 
III. Wash in water, 12 hrs. 
IV. Dehydrate, imbed, and cut 5 microns thick. 
Staining. V. Stain with iron-alum-haematoxylin (Heidenhain's 
method). 
This is the formula as given by Guilliermond, who has used it in much 
of his work. In my preparations it gave good results, at times, while again 
the results might be very bad, possibly due to impurities in the formalin 
The Benda fixation does just as well as a preparation for the iron-alum- 
haematoxylin as for the crystal violet-alizarin stain, this combination being 
often used. 
Corn 
In the root-tips of corn, of the "Canadian Early, Yellow Flint" variety, 
fixed according to Regaud's formalin-bichromate method, the time being 
shortened to four hours in the fixative (I), and eight hours in the bichromate 
(II), the cytoplasm in the embryonic region appears gray and filled with 
exceedingly numerous jet-black mitochondria, when stained with iron- 
alum-haematoxylin. In this region the mitochondria are globular, ellip- 
soid, or short rod-shaped. In the root-cap, next to the tip, they are similar, 
gradually lengthening from sHort rod-shaped to elongated, filamentous 
forms as one passes from the embryonic region toward the periphery of the 
cap. 
In the root-tip proper, passing back into the region of elongated cells in 
