1913] ECKERSON—AFTER-RIPENING 289 
MICROCHEMICAL METHOD 
In order to detect the metabolic substances of the cell as nearly 
unchanged as possible, observations must be made on the living 
tissue. Sections were made on a freezing microtome or free- 
hand, and intra-vitam stains (8) were used. Of the different 
‘methods and stains used, the following were found to be the most 
valuable. 
Fats.—Soudan III or Scharlach R, dissolved in 50 per cent 
alcohol. All fats are soluble in these stains. 
Lecithin.—The fats were first dissolved out with acetone, in 
which lecithin is not soluble. It was then stained with Soudan 
IIT, or blackened with fumes of osmic acid. 
Starch.—The sections were first heated in water on the slide, 
and then a drop of iodine solution added. 
Sugar.—For the reducing sugars Fehling’s solution was used as 
follows. The sections were heated in the copper sulphate solution, 
on the slide. The other part of Fehling’s solution, Rochelle salt 
and sodium hydroxide, was then added. Copper oxide is deposited 
in the cells containing sugar. Still better is the osazone test as 
modified by Mancuam (38). Dissolve phenylhydrazine hydrochlo- 
ride and sodium acetate in 10 times their weight of glycerin; warm 
to dissolve; filter once or twice. To use, put a drop of each on the 
slide, mix, put section of tissue in same. Place slide in warm oven : 
5-30 minutes, and then cool. Osazone crystals will be formed in the © 
cells which contained sugar. 
' Acidity or alkalinity—Neutral red, sulphate of Nile blue, 
Dahlia violet, and methyl orange. A 1/5000 solution of neutral 
ted is sensitive to N/11,000 NaOH; a 1/5000 solution of sulphate 
of Nile blue is. sensitive to N/s100 NaOH; the others are less 
Sensitive (Q). 
Catalase.—A drop of H,O, was put on the section on the slide 
and evolution of oxygen noted. 
Oxidase.—A few drops of freshly made solution of guaiaconic 
acid, on the slide. : 
Peroxidase.—A drop of H,O, added to a few drops of guaiaconic 
acid, put on the sections on the slide. 
