150 BOTANICAL GAZETTE [ AUGUST 
investigations show that about three-fourths of the ovules contain more than 
one embryo. A considerable percentage of the pollen is sterile and fertiliza- 
tion was not actually observed, although it probably occurs in many cases. 
Pollination is not necessary for the production of adventitious embryos, at 
least not for those coming from the nucellus. Whether an embryo would 
develop from an egg of Euphorbia without fertilization was not determined. 
Professor Hegelmaier withdraws his earlier statement that polyembryony, as 
found in Euphorbia, might lead to apogamy.— CHA s J. CHAMBERLAIN. 
IRREGULAR MITOSES in pollen mother-cellsand the consequent formation 
of imperfect pollen have already been noted in several sterile hybrids. In 
Cytisus Adami“ a hybrid between Cytisus Laburnum L. and C. purpureus 
Scop., the development of the pollen is regular, but abnormalities which 
result in sterility are found inthe ovule. After the integuments are quite well 
developed, a region at the base of the nucellus, rich in protoplasm, begins to 
grow with great rapidity, so that the nucellus is soon forced out through the 
micropyle. Often no megaspore mother-cell can be detected ; sometimes a 
larger cell with shrunken protoplasm and a few nuclei indicates’ that a 
mother-cell had begun to germinate, and occasionally when the. nucellar 
growth is not particularly extensive, a normal embryo sac may appear. In 
both the parents the development of the embryo sac is regular.— CHARLES 
J. CHAMBERLAIN, 
ZACHARIAS has published another paper™ on the chemistry and structure 
of the nucleus. The present contribution deals with the contents of the 
nucleus, exclusive of the nucleus and nuclein-containing structures. Pollen 
mother-cells of Larix, Iris, Hemerocallis, and other forms were investigated. 
Material was examined in the living condition and also after treatment with 
various reagents, but sections do not seem to have been used. In dealing 
with nuclei in division after the nuclear membrane has broken down, the 
special term, nuclear cavity (Kernraum), is used, because the sphere of 
influence of the nucleus may not be the same as when the nuclear membrane 
is still intact. The writer believes that Némec’s statement that the spindle 
fibers consist of plastin is too general. Plastin may be present in some 
cases, while in others it will be lacking. In the living cell during nuclear 
division the nuclear cavity, with the exception of the chromosomes, appears 
as if filled with a homogeneous fluid, in which movable thread-like structures 
may appear between the separating groups of chromosomes. Zacharias 
believes that his own investigations, as well as those of morphologists, show 
that definite spindle fibers have not yet been demonstrated in the living cell, 
and that it is possible that the structures seen in fixed material may be arti- 
facts.—CHARLES J. CHAMBERLAIN. 
*3 TISCHLER, G., Ueber eine merkwiirdige Wachsthumserscheinung in den Samen- 
anlagen von Cokes Adami Poir. Ber. Deutsch. Bot. Gesell. 21 : 82-89. f/. 5. 1903+ 
4 ZACHARIAS, E., Ueber die “ achromatischen” Bestandtheile des zellkerns. Ber. 
Deutsch. Bot. Gesell. 20: 298-320. A/. 76. 1902 
