444 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
divides usually into three, of which the middle one becomes the embryo- 
sac. The embryo-sac usually develops in the manner typical of Angio- 
sperms, but there may be a suppression of a normal egg-apparatus, and a 
formation of cellular tissue in the upper part of the embryo-sac before 
fertilisation. This is probably accompanied by an increase in the number 
of nuclei. The first division of the embryo is the typical one into two 
cells, a basal suspensor cell which remains permanently undivided, and a 
terminal embryo-cell. The cotyledon is derived entirely from the ter- 
minal one of the primary segments into which the embryo-cell first divides. 
The stem probably always originates from the second embryonal segment ; 
its position is strongly lateral. The root is of lateral origin, differing 
in this respect from other Monocotyledons which have been studied. 
Polyembryony in Opuntia.* * * § — Mr. W. F. Ganong describes the pro- 
cess of the formation of numerous embryos in Opuntia vulgaris. The 
embryos originate within the embryo-sac ; in half-ripe seeds there is 
frequently one springing from the micropylar end, and several from the 
walls. A careful examination shows that in both cases the embryos 
arise from the nucellus, When the pollen-tube reaches the micropylar 
region of the nucellus, no oosphere can be detected. It probably disap- 
pears early in the development of the ovule. Both the micropylar and 
the parietal embryos result from the budding of cells of the nucellus 
near the pollen-tube which are rich in protoplasm. In the course of its 
development the ovule assumes a campylotropous form, and becomes 
completely surrounded by the funicle. 
Centrosome-like Body in the Pollen-tube of Cycadese.f — Referring 
to the “ centrosome-like bodies ” found by Webber in the pollen-tube of 
Zamia, and the “ rounded nuclei ” observed by Belajeff in the sperma- 
togenous cells of Characem, Filicinese, and Equisetaceae, Prof. S. Ikeno 
comes to the conclusion, based on a comparison with similar structures 
in the animal kingdom, that the organs in question are true centrosomes 
which have become enormously distended, and serve as a surface of 
attachment for the cilia. 
Cross-Pollination and Self-Pollination. — Herr 0. Ekstam J names 
the insect visitors of a number of species, natives of Nova Zembla, 
together with the relative time of maturity of the stamens and stigma. 
Dr. P. Knuth § describes the contrivances for attracting insects in 
Leucojum vernum and Galanthus nivalis. In both plants, all the parts 
of the perianth, receptacle, and style which are not green contain 
honey. 
From observations and experiments on American species of Eupa - 
torium, Dr. Laura B. Cross || concludes that self-pollination is very rare ; 
and even when it does occur, the resulting fruits are of weak germinat- 
ing capacity. When cross-pollination by hand is effected, a slight 
increase is obtained in the production of good fruits ; but when covered 
* Bot. Gazette, xxv. (1898) pp. 221-8 (1 pi.). 
t Flora, lxxxv. (1898) pp. 15-8. Cf. this Journal, ante , p. 99. 
X Aftr. Tromso Mus. Arsk., xviii. (1897) pp. 109-98. See Bot. Centralbl., 
lxxiii. (1898) p. 14. 
§ Bot. Centralbl., Ixxiv. (1898) pp. 161-5 (1 fig.). 
II Contrib. Bot. Lab. Univ. Pennsylvania, i. (1897) pp. 260-9 (1 pi.). 
