020 
that the animal pole of turtle and other 
vertebrate eggs is electronegative to the vege- 
tal pole, and the anterior ends of vertebrate 
embryos electronegative to posterior regions. 
Child® subsequently found in similar mate- 
rials that the electronegative regions are also 
regions of high metabolic rate. Morgan and 
Dimon?® reported that the anterior and poste- 
rior ends of Lwmbricus terrestris and Allolobo- 
phora (Helodrilus) fetida are electronegative 
to the middle. Mr. Bellamy has repeated this 
experiment and confirmed the result on Helo- 
drilus caliginosus. In my work on the aquatic 
oligocheetes,11 I was able to show in a number 
of species that the anterior and posterior ends 
have a higher metabolic rate than the middle. 
The same state of affairs presumably exists in 
the terrestrial oligochetes also, although these 
ean not be tested by the available methods for 
demonstrating differences in metabolic rate. 
In these cases the regions of high metabolic 
rate are always permanently electronegative 
hydranths appear earlier on apical than on basal 
pieces. In animals so lowly organized as the hy- 
droids, where the metabolic gradient is well 
marked only near the apical end, practically lack- 
ing near the base, and very plastic and readily 
alterable by external factors, it is easy to select 
conditions under which the basal pieces will re- 
generate hydranths as fast as or faster than the 
oral ones; such conditions are: using long pieces, 
taking pieces from the more basal regions of the 
stem instead of from the apical regions, using basal 
pieces near the place where a branch is about to 
form, slight depressing conditions, ete. (the mere 
fact that pieces do well in the laboratory is not 
evidence that no depression existed; in fact, de- 
pressed pieces are more likely to survive than vig- 
orous ones). Since Garcia-Banus mentions none of 
these factors in his paper, not even stating whether 
his apical pieces are near the original hydranth or 
not, it is presumable that he failed to control or 
eliminate them, and that this explains why he was 
unable to obtain the same results as other investi- 
gators. 
8 Am. Jr. of Physiol., XII., p. 241. 
9 This work is largely unpublished. See, how- 
ever, on amphibian embryos, Child, Roux’s Archiv, 
XXXVII., p. 135. 
10 Jr. Hap. Zool., I., p. 331. 
11 Jr. Exp. Zool., XX., p. 99. 
SCIENCE 
[N. 8. Von. XLVIII. No. 1247 
to regions of lower metabolic rate. This fact 
suggests the hypothesis that the metabolic 
differences are directly responsible for the 
differences in potential and that the latter are, 
therefore, of chemical origin. This is also the 
opinion of Child, and R. S. Lillie has recently 
come to a similar conclusion.!2 I am also in 
accord with R. S. Lillie regarding the chem- 
ical process which is at the bottom of these 
differences in potential,_namely, that it is an 
oxidation and reduction phenomenon. In 
considering this matter, one must remember 
that when one states that a given region is 
electronegative, one means electronegative 
with respect to the galvanometer, exactly as 
one says that the zine pole of a cell is the 
negative pole; actually the zine pole is positive 
to the carbon or copper pole, and similarly the 
regions of high metabolic rate are in reality 
electropositive to regions of lower metabolic 
rate. If one considers now the familiar “ ac- 
tion at a distance” experiment of chemistry, 
in which the oxidation is carried out in one 
beaker, and the reduction in another, one finds 
the electrical conditions thus produced to be 
identical with those observable in organisms. 
The current runs in the galvanometer from 
the reduction beaker to the oxidation beaker, 
and in the bridge of salt solution from the 
oxidation beaker to the reduction beaker. 
The region of oxidation is thus, as also in the 
region of high metabolic rate in the organ- 
ism, electronegative galvanometrically, actually 
electropositive. We have abundant evidence 
that the metabolic gradient runs parallel to 
the rate of oxidation. In the organism, how- 
ever, oxidation and reduction are not sep- 
arated as in our experiment, but there in all 
probability, the electric difference of potential 
is due to difference in rate of oxidation at 
difference levels,—in other words, to a con- 
centration cell with respect to oxidation. 
2. The Current of Injury—tIt has long been 
known that any cut or injured surface is 
electronegative (galvanometrically as explained 
above) to intact surfaces. In this laboratory 
we have frequently observed that such injured 
surfaces always have a higher metabolic rate 
12 Biol. Bull., XXXIII., p. 181 ff. 
