ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
387 
style the generative is usually somewhat in the rear of the vegetative 
nucleus, and differs from it in not being distinctly nucleolated. The 
generative nucleus continues to increase in size, while the vegetative 
nucleus rather diminishes. The former now divides into two, and the 
two secondary generative nuclei are equivalent in structure and in func- 
tion ; each of them has the power of fecundating the oosphere ; but the 
object of this bipartition is not evident ; each is furnished with its pair of 
directing spheres. The vegetative nucleus has disappeared by the time 
the pollen-tube has come into contact with the 7iucellus. After fecunda- 
tion has taken place, the second generative nucleus is frequently seen 
close to the active male nucleus inclosed within the oosphere, but without 
uniting with the female nucleus. 
The typical example of Lilium Martagon is closely compared by the 
author with the phenomena presented by other plants, e. g. Fritillaria 
imperialis, Muscari comosum, Agraphis cernua, Alstrcemeria psittacina, &c. 
As regards the actual process of fecundation, no change is perceptible 
in the female nucleus until the male nucleus has itself come to rest ; 
the latter has by this time increased in size, and its chromatic elements 
have become distinct, forming a network or framework. Its final size 
is, however, somewhat less than that of the female nucleus, though the 
quantity of chromatic substance appears to be the same in both. The 
rapidity of the union of the two nuclei varies greatly in different plants. 
Since the chromatic elements of the two nuclei do not unite, the process 
of fecundation must be regarded simply as a mixing of the soluble sub- 
stances, the nuclear fluid and the product of resorption of the nucleoles. 
The bearing of the facts above described on the various theories of 
impregnation and heredity is discussed at length. 
Commenting on this paper, Herr E. Zacharias * maintains that, at the 
moment when the male nucleus enters the female nucleus, the two differ 
materially from one another in their morphological structure and in 
their chemical composition. It is possible that the amount of chromatin 
in the two may be the same before their uniun ; but, owing to the differ- 
ence in their size, the percentage composition differs considerably. 
Abnormal Embryos of Nuphar.t — Herr F. Hegelmaier describes 
several abnormal embryos of Nuphar liiteum in which the two cotyledons 
are more or less completely united into a sheath, split only on one 
side ; but the two halves (corresponding to the two cotyledons) have 
developed very unequally, one of them being usually several times as 
long as the other. 
Parasitic Castration by TJstilago antherarum. — According to M. 
P. Yuillemin,j; the abortion of the ovaries of Lychnis dioica resulting 
from the attacks of this parasitic fungus is not complete, some of the 
ovules frequently escaping injury, and being fertile. He also states 
that the production of fertile stamens in the female flowers, said to 
result from the attack of the fungus, is entirely illusory. It does, no 
doubt, cause hypertrophy of the rudiments of stamens which always 
* Bot. Ztg., 1. (1892) pp. 246-8. 
f J.Heft. Ver. vaterl. Naturk. AVurtemberg, 1890, pp. 88-97 (1 pi.). See Bot 
Centralbl., xlix. (1892) p. 216. 
J Comptes Rendus, cxiii. (1891) pp. 662-5. Cf. this Journal, 1890, p. 744. 
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