656 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
well-nourished they are erythrophilous, while a stoppage of the absorption 
of nutriment from the cytoplasm renders them cyanophilous. The 
sexual cells of Gymnosperms are erythrophilous in proportion to the 
mass of cytoplasm by which they are surrounded. The nuclei enclosed 
in the small prothallium-cells are mainly cyanophilous, while the nucleus 
of the pollen-grain is erythrophilous, where the protoplasm, with the 
generative cell, makes up only a small portion of the pollen-grain ; 
in Ephedra, where it occupies three-quarters of the pollen-grain, it is 
cyanophilous. 
For the attractive spheres the author proposes the term astrosphere , 
and for the astrosphere, together with the surrounding centrosome, 
centrosphere. Astrospheres were detected in Sphacelaria , but they differed 
from those of higher plants in not doubling in number during karyo- 
kinesis. The term kinoplasm is applied to the hyaline constituents of 
protoplasm, which take part in active movements, but under the in- 
fluence of kinetic centres. In (Edogonium it is especially the kinoplasm 
which collects at the mouth of the archegone. The bladder, which 
encloses the swarmspore as it escapes, is the modified parietal utricle of 
the sporange. In other Algas also, and in some Fungi, the kinoplasm 
and astrospheres play an important part. 
In the formation of the antherozoids of Chara, the author agrees 
with the statement of Belajieff,* the cytoplasm taking part in their forma- 
tion, especially in the production of the cilia. In ferns also the two 
anterior coils of the antherozoids are of cytoplasmic origin, and the 
same is true of the cilia in the Muscinete. Neither in Characeae nor in 
Muscineae can he detect the spiral structure described by Schottlander.f 
As a general conclusion, the author states that three constituents of 
the protoplasm take part in the process of impregnation, viz. the nucleus, 
the centrospheres, and the kinoplasm. 
Embryogeny of the Birch.f — According to M. S. Nawaschin, the 
mode of impregnation of the birch differs in several points from that of 
typical Angiosperms, approaching the mode seen in the Chalazogams.§ 
The nucleus is differentiated into an outer tissue composed of short, and 
an inner one of elongated cells ; one cell of the latter becomes the 
embryo-sac. The pollen-tube never enters the cavity of the ovary, but 
grows into the tissue of the upper part of the suspensor, forces itself 
through the chalaza, and finally reaches the tissue of the nucleus at the 
apex of the embryo-sac. In the formation of short lateral branches, and 
in the constrictions, the pollen-tube of Betula also resembles that of 
Casuarina. 
Dr. 0. Fritsch || argues from this discovery the inadequacy of the 
mode of impregnation as a character for separating off the Casuarineee 
as a distinct class of Angiosperms. 
Distribution of Sexual Organs in Plants. — Herr F. Hildebrand % 
records examples of the replacement of male by female flowers in 
* Cf. this Journal, 1892, p. 237. t Cf. this Journal, ante, p. 203. 
% Bull. Acad. Imp. Sci. St. Petersbourg, xiii. pp. 345-8. See Bot. Centralbl., liv. 
(1893) p. 237. § Cf. this Journal, 1892, p. 230. 
II SB. K. K. Zool.-Bot. Gesell. Wien, xliii. (1893) pp. 15-6. 
i Bot. Zt,g., li. (1893) l ,e Abtheil., pp. 27-35 (1 fig.). 
