462 
the absorption of nourishment from the fluids of 
the intervening spaces. 
If a mechanical stimulus is applied to the 
middle of the column of a Metridiwm, in some- 
what less than a minute a well-marked constric- 
tion encircles the animal, due to the contraction 
of the circular muscles of the column. This con- 
striction will occur on a column whose ectodermic 
surface has been anesthetized with magnesium 
sulphate to such an extent that the characteristic 
retraction reflex can not be called forth from 
it. It is therefore probably a non-nervous direct 
response of the muscle comparable to the direct 
responses already demonstrated in the muscles of 
some sponges. 
The Structural Changes during the Contraction of 
Mollusk Muscle: Utric DAHLGREN, Princeton 
University. 
The Organs of Equilibration in Pelecypod Mol- 
lusks: ULRIc DAHLGREN, Princeton University. 
Preliminary Chemical Studies on Male and Fe- 
male Producing Eggs of Pigeons: A Study of 
the Eggs of Forms in which the Dominance of 
Male and Female Sex and of White and Dark 
Color was Experimentally Determined by Pro- 
fessor C. O. Whitman: OscaR RIDDLE, Univer- 
sity of Chicago. 
Much more important than the results of these 
preliminary chemical studies are the hitherto un- 
announced facts upon which the studies are based. 
One of the remarkable results achieved by Pro- 
fessor Whitman in his work with pigeons is the 
experimental control of the sex and color of the 
offspring of certain crosses of pigeons. That is to 
say, one and the same pair of birds can now be 
made to produce only dark male offspring—in 
spring and early summer, and when birds are 
young and in full reproductive vigor; and likewise 
only white female offspring—in late summer and 
autumn, and when birds are very old. The method 
consists simply in the choice of birds of known 
age and vigor for the matings, and then removing 
their eggs as fast as laid to other birds—thus 
forcing the birds throughout the year to their 
maximum of egg-production. All of the first sev- 
eral pairs of eggs produce dark male hybrids; 
while all of the last several pairs produce white 
female hybrids. A short transition period inter- 
venes in which the sex and color of the progeny 
can not be foretold. There is usually a final 
period in which eggs are produced capable of 
little, and of no development. Birds thus treated 
over a period of years show that fewer and fewer 
SCIENCE 
[N.S. Vou. XXXV. No. 899 
males are produced each succeeding year, and that 
the time of appearance of female-producing eggs 
is moved more and more toward the beginning of 
the season. Finally, matings of very old birds can 
be made in which it can be definitely foretold that 
only white female offspring will be produced. 
These results have been verified yearly since 1903. 
It is necessary of course to mate individuals of 
two different species, varieties or hybrids (one 
bird dark the other light if color is to be con- 
trolled) for such control. Four pure species (re- 
ciprocal crosses) and four different kinds of 
hybrids were successfully used in this way. Stated 
in Mendelian terms—terms which Professor Whit- 
man did not think it well to use—he was able to 
shift, control or determine experimentally the 
dominance of sex and color. Aside from the fact 
that this discovery by Professor Whitman fur- 
nishes a starting point and a background for my 
chemical studies, it unfortunately seems necessary 
to emphasize at this time, that, although Professor 
Whitman had never announced this result, he had 
obtained it as early as 1903; and that this result 
—confidentially communicated—has been well 
known to his colleagues at the University of 
Chicago practically since that time. 
The result of a limited number of parallel in- 
cubations and analyses made in 1911 on the male- 
producing and female-producing eggs obtained 
from the above-mentioned crosses indicate (num- 
ber too small for final decision): (1) That eggs of 
smaller size, higher water content and smaller 
energy content (v. e., fewer units of physiologically 
available energy) can be correlated with maleness 
and dark color in the offspring. (2) That eggs of 
larger size, lower water content and greater en- 
ergy content can be correlated with femaleness and 
white color in the offspring. 
On a Relation Found to Exist between Changes in 
the Chemical Composition of a Membrane and 
Changes in its Permeability: Oscar RIDDLE and 
ADELAIDE A. SPOHN, University of Chicago. 
The follicular membrane can be taken for an- 
alysis at three different phases of its normal per- 
meability to the constituents of yolk, viz: (1) 
When these constituents are penetrating the mem- 
brane very slowly; (2) when a sudden and very 
great increase in this rate of penetration occurs; 
and (3) the period following this increase and 
during which the greatly increased permeability 
is also accompanied by a rapid proliferation of the 
component cells of the membrane. Analyses show 
that in phase (1) when the permeability and 
