NoveMBER 22, 1918] 
freely soluble)!® yields a dough quite as easy 
to handle as that produced from pure wheat 
flour. Such a dough does not, like ordinary 
doughs containing substitutes, easily become 
“ overproved.” The loaves do not fall in the 
oven, for the serum proteins decrease the leak- 
age of carbon dioxide from the dough.2® The 
danger of the loss of a whole batch from ex- 
cessive fermentation is therefore minimized. 
The use of serum proteins in this way ma- 
terially lessens the very real difficulties which 
now exist. Moreover the resulting loaf is 
larger and more elastic, of better color and 
texture, and in all respects superior to loaves 
containing equal amounts of wheat substitutes 
but lacking serum. If it is inferior to bread 
made of pure wheat flour, it possesses certain 
important qualities of its own, and its use 
seems to be in all respects quite unexception- 
able. 
ROPE 
Ropy bread is produced by the action of 
certain microorganisms whose spores survive 
the heat of the oven and later, when the con- 
ditions. are favorable, attack the center of the 
loaf. At a temperature of about 26° C. (80° 
F.) their growth is rapid. For this reason 
epidemics of rope occur in summer. The 
principle organisms which cause rope belong 
to the B. mesentericus group. 
Another condition which is necessary for 
the development of the rope organism is low 
acidity.2:_ Bread which is sufficiently acid is 
quite immune. It is therefore possible ab- 
solutely to prevent rope by sufficiently in- 
creasing the acidity of dough. It has been 
found that the degree of acidity which is 
otherwise most favorable in ordinary bread 
making, at least as practised both in Amer- 
ica’, 16 and in Denmark" js sufficient for this 
purpose. This acidity is indicated by a full 
19 Burrows, G. H., and Cohn, E. J., ‘A Quanti- 
tative Study of the Evaporation of Serum Pro- 
teins,’’ Jour. Biological Chemistry, 1918. 
20 Unpublished observations. 
21 Cohn, E. J., Wolbach, S. B., and Henderson, 
L. J., ‘‘The Control of Rope,’’ Jour. of General 
Physiology, Vol. 1, No. 2, 1918. 
SCIENCE 
505 
red color when a few drops of a solution (0.02 
per cent. in 60 per cent. alcohol) of the in- 
dicator methyl red are placed upon a slice of 
bread. Bread should be adjusted to this acid- 
ity, especially when there is danger of an 
epidemic of rope. This is best done by the 
addition of increasing amounts of acid to 
the dough of successive batches until the 
baked loaf gives the desired color. Generally 
the right amount of lactic acid is between 
one and two pounds of the commercial prod- 
uct (22 per cent—25 per cent.) per barrel of 
flour. (This corresponds to 1.25 ¢.c. normal 
lactie acid in 100 g. flour.) 
It has been pointed out that wheat substi- 
tutes usually combine with more acid than 
wheat flour itself. In this way they neutral- 
ize the acidity of the dough and as a result 
the greater the amount of substitute the 
greater is the amount of acid that must be 
added to bring bread to the acidity indicated 
by a red color of methyl red. The preference 
of the baker for “young” doughs and the 
greater capacity of the substitutes to neutral- 
ize acids is the reason why rope has caused so 
much trouble during war time. 
We are indebted to the Carnegie Institution 
of Washington and to Professor Theodore W. 
Richards for the use of much valuable and in- 
dispensable apparatus, without which our re- 
searches could hardly have been carried out. 
It is a great pleasure to express our thanks for 
this aid. 
E. J. Cony, 
L. J. Henprrson 
INDUSTRIAL RESEARCH AND 
NATIONAL WELFARE! 
Art the outbreak of the war the average 
statesman of the Allied powers was but little 
concerned with the interest of research. Ne- 
cessity, however, soon opened his eyes. He be- 
gan to perceive the enormous advantages de- 
rived by Germany from the utilization of sci- 
1 From an address delivered by Dr. George E. 
Hale under the auspices of Engineering Founda- 
tion in the Engineering Societies Building, New 
York, May 28, 1918. 
