1g1t] SCHREINER & SULLIVAN—REDUCTION BY ROOTS 123 
to a great degree. Rery-PAILHADE (16) extracted from yeast cells 
by means of alcohol a substance which would form H,S from S. To 
this substance he gave the name philothion. He found it likewise 
in fresh animal tissues, in the tips of young shoots of asparagus (17), 
and in various grains and young seedlings (18). Pozzr Escor 
(19) verified Rey-ParLHapE’s work and succeeded in hydrogenat- 
ing in addition metallic selenium and phosphorus. PALLADIN 
(20) found a reductase in wheat shoots and concluded that it 
played a part in respiration. DELEANO (21) found a reductase 
or hydrogenase in the albumen of Ricinus communis, but not in the 
roots or the plantules. The albumen triturated with sulphur gave 
hydrogen sulphide. LauRENT (22) showed that young seedlings 
reduce nitrates and that there can be extracted from plants an 
unorganized ferment which has the power to convert nitrates to 
nitrites. ABELOUs and ALoy (23) found a nitrate-reducing enzyme 
in potato tubers. KastLEe and ELvove (24) confirmed the presence 
of the nitrate-reducing enzyme in the potato and showed that it 
was present also in the fruit of the egg plant (Solanum melongina). 
Recently Irvine and HANKINSON (25) have found nitrate-reducing 
enzymes in certain water plants. 
Since little has been done upon the reducing power of seedlings 
growing in soil or solutions, experiments were made to determine 
the power of the intact and growing roots, especially of wheat, to 
reduce substances, with the ultimate purpose of seeing if, like 
the oxidative power, the reducing power would be found to play a 
significant part in soil fertility. 
Various dyes such as methylene blue, indigo carmine, Bismarck 
brown, gentian violet, etc., were first employed to see if the roots 
would decolorize the solution in which they were growing. The 
color of dilute solutions of the dyes was greatly lightened by the 
growing roots, especially if air was excluded. Since, however, 
more or less of the dye-stuff was deposited on the outer surface 
of the root and root hairs, such solutions were not considered satis- 
factory for showing reduction if this occurs. 
STARCH IODIDE SOLUTION.—When wheat seedlings are placed 
in dilute solution of blue starch iodide with seeds and roots in the 
solution, the blue color is soon discharged. With the roots only in 
