460 
Morphologie, Befruchtung, Teratologie, Cytologie. 
N. C., crops of sexual cells are produced at monthly intervals, 
bearing a definite relation to the tides. Light is not the sole factor 
determining the fruiting. Charles J. Chamberlain (Chicago). 
Kirkwood, J. E., Some Features of Pollen-Formation in 
the Cucurbitaceae. (Bull, of the Torrey Bot. Club. Vol. XXXIV. 
1907. p. 221-242. Pis. 17—21.) 
The development of the pollen grains from the pollen mother 
cell was studied in several genera. As the first mitosis approaches, 
the chromatin becomes distributed in paired masses throughout the 
nuclear reticulum. The masses merge as synopsis begins. In the 
telophase of the second mitosis the chromatin distributes itself in 
the form of a beaded network which persists for a long time. 
Charles J. Chamberlain (Chicago). 
Land, W. J. G., Fertil ization and Embryogeny in Ephedra 
trifurca. (Botanical Gazette. Vol. XLIV. p. 273—292. pls. 20—22.) 
The concluding paper of Land’s studies of Ephedra trifurca deals 
with fertilization and embryogeny. The two male cells are equal in 
volume and optical appearance and fertilization is possible within 
ten hours after pollination. One male nucleus fuses with the egg, 
which promptly divides, giving rise to eight free nuclei more or 
less unequal in size, and of which from three to five produce em- 
bryos. The second male nucleus come to rest in the upper part of 
the egg, enlarges and finally extends out into the space formerly 
occupied by the jacket cells, which about this time have lost their 
walls and have mingled their contents with the cytoplasm of the 
egg. The second male nucleus finally loses its membrane and soon 
afterward its place is filled with minute cells, as is also the cyto¬ 
plasm of the egg, and the jacket cells. This ephemeral mass of small 
cells is quickly absorbed by the functioning embryos. It is suggested 
that at least some of this mass of cells is due to the interaction of 
the chromatin of the second male nucleus with the chromatin of the 
jacket nuclei and perhaps also with that of the minute functionless 
pro-embryonal nuclei. This ephemeral mass of small nuclei surroun- 
ding the functioning pro-embryonal nuclei is believed by the writer 
to be, if not the beginning, at least the fore-shadowing of the en- 
dosperm of angiosperms. 
Each of the functioning pro-embryonal cells produces two free 
nuclei. A suspensor tube is put out, and one of these free nuclei 
passes into the tube and a cell is cut off by constriction similar to 
formation of cell walls in many algae. The second nucleus then 
passes into the suspensor which rapidly elongates. A secondary 
suspensor which merges insensibly into the root cap is cut off from 
the basal cells of the embryo. Under conditions favorable forgrowth, 
the seed does not rest. The time from the setting of strobili to the 
appearance of the young plant is about six months. 
A comparison of the gametophytes of Ephedra trifurca with 
those of other gymnosperms leads the author to conclude that while 
the male gametophyte is relatively primitive the female gametophyte 
has made a decided advance toward the angiosperm level; that the 
Gnetales are a consistent group, Ephedra being the most like Coni- 
ferales, with Tumboa perhaps nearer to the Gnetum level than to 
Ephedra . 
