936 
the reorganization of the remainder of the piece. 
The head forms ‘‘in spite of’’ other old parts of 
the piece and not in correlation with them, but the 
new posterior end is the product of correlation 
with more anterior parts. In a series of similar 
pieces the frequency of head-formation and the 
character of the heads can be altered in either 
direction by agents which influence the rate of 
metabolism. 
Observations on the Breeding Behavior of the 
Herring Gull: R. M. Srrone, University of 
Chicago. 
Studies were made of the breeding behavior of 
the herring gull from the standpoint of modifia- 
bility, and especial attention was given to the 
voice of this bird. The report was illustrated by 
lantern slides. (To be published elsewhere.) 
(1) Maturation and Fertilization of the Arma- 
dillo Ovum. (2) Crucial Evidence of Partheno- 
genetic Cleavage of Ova during Follicular 
Atresia in the Armadillo: H. H. NEWMAN, Uni- 
versity of Chicago. 
(1) The armadillo ovum is probably the most 
primitive Eutherian ovum known, in the sense 
that it shows a condition practically like that of 
the Marsupial Dasyurus. In the full-grown ovo- 
eyte there is a cortex of formative protoplasm and 
a central deutoplasmic mass. During the process 
of maturation a radical change of polarity takes 
place, resulting in ‘‘telolecithal’’ condition upside- 
down. The deutoplasmie mass occupies the animal 
pole and the formative protoplasm lies at the 
vegetative pole in the form of a cap partially over- 
lapping the deutoplasm. The maturation spindle 
is found in an equatorial position, % e., as near 
the animal pole as possible without leaving the 
formative protoplasm. In other respects the 
maturation processes are essentially like those of 
other mammals. Only one fertilized egg was 
found, but this is very typical and is accepted as 
the norm for the species. There is but one male 
and but one female pronucleus and there are the 
usual two polar bodies. This furnished additional 
proof of the reality of polyembryony in the species. 
The present investigation is the first study of 
maturation or fertilization processes in the Eden- 
tates. (To appear in Biological Bulletin.) 
2. All previous observations concerning the al- 
leged occurrence of parthenogenetic development 
in the mammalia have met with scant attention on 
the part of biologists. It is hoped that the present 
observations will meet a better fate. The follow- 
ing phenomena have been observed in ovarian ova 
SCIENCE 
[N. 8. Vou. XXXV. No. 911 
that have reached maturity but have been robbed 
of their chances of ovulation by the occurrence of 
pregnancy. The mature ovum, which has the con- 
dition described in the previous abstract, gets rid 
of its deutoplasmie mass by abstriction. The for- 
mative protoplasm then rounds itself up into a ball 
within which lies the large resting nucleus, prob- 
ably the female pronucleus; the latter then forms 
a perfect cleavage spindle whose aster radiations 
invade the entire cell, and the first cleavage occurs. 
Equally unequivocal cleavage spindles occur in each 
of the first two blastomeres. Stages have been 
found with as many as four spindles visible at 
one time. In others two or three spindles and one 
or two resting nuclei occur in the same egg. The 
fate of the deutoplasmic material is peculiar and 
probably quite different from that in normal de- 
velopment. It fragments into a large number of 
cell-like bodies, with nucleus-like corpuscles com- 
posed of deutoplasmie granules, and at first forms 
a sheath around the formative cells. Subsequently 
these fragments are crowded between the blasto- 
meres and bring about a condition of isolation of 
blastomeres. Evidently cleavage goes on consid- 
erably further, but, since there is at this time a 
tendeney for stroma cells to enter the egg through 
breaks in the zona pellucida, it is impossible to be 
sure as to how much of the observed conditions 
are due to the development of the egg and how 
much is to be attributed to the activities of in- 
vading cells. The first few cleavages, however, are 
certainly the result of parthenogenetic develop- 
ment of the ovum. (To appear in Journal of 
Morphology.) 
Preliminary Chemical Studies on Male and Female- 
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 Professor C. 
O. Whitman: Oscar RIDDLE, Carnegie Insti- 
tution. 
(Abstract published in ScIENCE, March 21, 1912, 
p. 462.) 
Indications Regarding Differentiation from Tissue 
Culture Experiments: MARIAN L. SHOREY, Mil- 
waukee Downer College. 
Tissues of dogfish embryos from five to fourteen 
millimeters in length were found to grow equally 
well in saline solutions that contained, and those 
that did not contain, nutrient substances. As 
there seems to be no evidence that the embryonic 
cells of animals in which there is a distinct separa- 
tion between the germ plasm and the yolk, as is 
