122 BOTANICAL GAZETTE [FEBRUARY 
blue and the more easily reduced indophenol blue, both of which 
on reduction give colorless bodies. ‘On injecting these colored 
substances he found that organs of the animal could reduce them 
to the leuco-bases. Enriicu divided the organs of the body into 
three main groups: (1) those highly saturated with oxygenin 
which indophenol blue remains; (2) those in which indophenol blue, 
but not alizarin blue is reduced; (3) those of highest oxygen avidity, 
in which alizarin white is formed. 
In the first group are the gray matter of the nervous system, 
heart, part of the muscular system, and kidney capsule; in the 
second group, most of the muscular system, glands, and connective 
tissue; in the third group, the lungs, liver, fat, Harder’s gland, and 
mucosa of the stomach. 
Since Eurticu’s experiments, the reducing power of animals, 
plants, and microorganisms has been extensively studied. The 
reagents used to demonstrate the reducing power are numerous. 
Among them are various colored substances which form leuco- 
bodies, such as lacmus, methylene blue, indigo carmine, indigo 
blue, gentian violet, methyl violet, rosaniline, etc.; nitrates, which 
are reduced to nitrites; sodium selenite and sodium tellurite, which 
are reduced to metallic selenium and tellurium. Methylene blue 
and lacmus are used most. The former is converted to a leuco- 
base by the addition of hydrogen, the latter apparently by the 
abstraction of oxygen. 
Reduction has been studied more extensively in the case of 
microorganisms than in animals and plants. Whether the reduc- 
tion produced by microorganisms is due to enzymes or not has not 
yet been settled. Rozsanecyr (5), Bacinsky (6), MULLER (7); 
and Wotrr (8) believe that the reduction is caused by external 
metabolic products; while CaAHEN (g), SPINA (10), SMITH (11), 
KLeTtT (12), MAASSEN (13), and Catucart and Haun (14) regard 
it as an attribute of the bacterial cell. They all agree, however, 
that the reduction is associated with the development of bacteria. 
In regard to reduction in higher plants, it might be mentioned 
that Buyz and Scuurz (15) found that plant protoplasm had the 
power of reducing arsenic acid (As,O;) to arsenious acid (As,03); 
while plant protoplasm treated with boiling water lost this pow! 
