756 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
flora). He finds no evidence to support the statement of the parasitic 
habit of the genus. On the other hand the cells of the cortical tissue 
contain a great quantity of septate hyphal filaments which readily pierce 
the cell-walls and are sometimes continued outside the stem ; they are 
only rarely found in the epiderm. They appear to belong to a true 
symbiont, supplying, from the decaying vegetable matter which sur- 
rounds the rhizome, the greater part of the nutrient substances required 
by the plant. 
£. Physiology. 
Cl) Reproduction and Embryology. 
Embryo-sac and Embryo of Senecio aureus.* — Mr. D. M. Mottier 
has examined the structure and development of these organs in this 
species, and finds that they differ in some respects from those described 
by Strasburger in S. vulgaris. The nuclei of the synergids lie im- 
bedded in the protoplasmic lining of the cell, about midway between 
the anterior and posterior ends, not in the posterior third, as in the case 
of S. vulgaris. The antipodals occupy the entire posterior end of the 
embryo-sac, lying in a longitudinal row. They are not absorbed during 
the formation of the endosperm, but persist throughout. The suspensor 
consists of only a few cells, usually three or four. The endosperm cells 
are relatively large, and not very rich in protoplasm, while the layer of 
cells which forms the wall of the embryo-sac, and which is the modified 
adjacent part of the integument, is rich in protoplasm and nuclei. 
Pollen-tube of Gymnosperms.f — Pursuing his researches on this 
subject, Herr W. Belajeff now compares the results obtained in Taxus 
with those from other divisions of the Coniferse, especially the Abietineae 
and Cupressineae. In the Abietineae we find the most complex structure ; 
at the base of the pollen-tube are two small motionless cells, which 
must be regarded as the vegetative cells of the prothallium ; the remain- 
ing cells from which the tube is formed are the homologue of the 
antherid of cryptogams. This antherid consists of a large outer cell 
which lengthens into the tube and corresponds to the parietal cells, and 
of an inner cell homologous with the mother-cell of the antherozoids. In 
the Abietineae the inner cell divides into three ; the two anterior ones 
take part in the impregnation, while the posterior cell becomes dis- 
organized. In the Cupressineae the pollen-tube has a much simpler 
structure. Here there are no small motionless cells, and the male 
prothallium is reduced to an antherid. The small inner cell divides 
into three, of which two take part in the process of impregnation. In 
Taxus , on the contrary, the anterior inner cell does not divide into two, 
but expels its nucleus, and there is only one fertilizing cell. 
In Phanerogams the author maintains, therefore, in opposition to the 
view of Strasburger, £ that it is the inner cell of the pollen-grain which 
is the active agent in impregnation. 
Andrceceum and Gynoeceum of Grasses.§ — Herr St. J. Golinski has 
studied the development of the sexual organs in a number of Gramineae 
belonging to different tribes. 
* Bot. Gazette, xviii. (1893) pp. 245-53 (3 pis.). 
f Ber. Deutsch. Bot. Gesell,, xi. (1893) pp. 196-201 (1 pi.). Cf. this Journal, 
1892, p. 231. X Cf. this Journal, ante, p. 655. 
§ Bot. Centralbl., lv. (1893) pp. 1-17, 65-72, 129-35 (3 pis.). 
