124 BOTANICAL GAZETTE [FEBRUARY 
the starch iodide solutions, the color is discharged slowly. The 
addition of hydrochloric acid to the decolorized solution brings 
back the blue color. Reducing agents such as sodium thiosulphate, 
formaldehyde, hydrogen sulphide, etc., behave similarly. 
Seedlings were kept in water solution of iodine of o.o12 per 
cent strength of iodine for two hours with: (a) seeds and roots in 
iodine solution; (b) roots only in iodine solution; and (c) control 
in which no plants had been. Solution (a) gave no color on addition 
of the starch; (b) gave a slight blue color; and (c) gave a deep 
blue. 
On addition of a few drops of concentrated hydrochloric acid, 
all the solutions became deep blue and no difference could be seen 
in the depth of color. It would seem then that the plants hydro- 
genate the iodine, forming an iodide from which the acid liberates 
the iodine, or that the plants in some way render the iodide inactive 
toward the starch. 
Since the chemistry of the starch iodine combination is not 
sufficiently known, and since the intensity of color produced by the 
reaction between starch paste and iodine is by no means quantita- 
tive, the effect the seedlings had on this reaction was taken merely 
as a sign of the possibility of a hydrogenase or a reductase in the 
seedlings, seed, or root. 
SuLPHUR.—The roots and the seed and roots of the intact seed- 
ling were put in contact with well washed, precipitated sulphur, 
neutral, made slightly acid with hydrochloric acid, or slightly alkaline 
with sodium hydroxide. In no case was hydrogen sulphide detected 
by means of lead acetate paper. Alcoholic extracts of the crushed 
seedlings after the method of Rrey-PartHapE (16), and Pozzi- 
Escor (19) were likewise found to have no hydrogenating action 
on precipitated sulphur. 
HEFFTER (26) found that compounds containing the sulphydryl 
or SH group such as thiophenol, benzylmercaptan, ethylmercaptan, 
thioglycolic acid, and cystein reduce sulphur, and came to the 
conclusion that the reducing power of cells is due to the labile 
hydrogen of sulphydryl compounds which give up their hydrogen 
and become disulphides. This sulphydryl group is present i 
certain albumins, and is shown by a purple-red coloration with 
