ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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an insoluble state, and which are seen as granulations in Lilium can- 
didirn. At the same time the nucleole becomes slowly incorporated 
with the filament, the folds of which swell, and part disappears. The 
filament becomes knotted, and subsequently unrolls. During the knot- 
phase it becomes detached from the nuclear membrane. When the 
nucleus is completely filled, and the membrane can no longer stretch, 
the osmotic interchanges between the cell and the nucleus almost 
cease. The end of this first phase is characterised by the complete 
dissolution of all the insoluble substance of the caryoplasm, all the 
granulations disappearing, as in Lilium candidum. But in Spirogyra it 
is possible to detect the product of the dissolution of the granulations, 
in the form of a new, completely homogeneous caryoplasm. The forma- 
tion can be followed of the achromatic filaments from this caryoplasm, 
while the nuclear cavity is still provided with its membrane, although 
the author had previously erroneously stated the contrary. 
The second phase commences at the period when the nuclear mem- 
brane becomes more permeable, especially in its two opposite portions 
which are most removed from the cell- wall. This appears to be the 
result of the direct action of the caryoplasm, which passes through it 
and enters the cell. The cell-sap at the same time enters the nucleus, 
which gradually swells until the formation of the plate. 
The details of these processes are minutely described in the case 
of Spirogyra crassa. 
Abnormal Nuclei in the Endosperm of Fritillaria imperialist — 
Mr. H. H. Dixon observes that, before direct fission, nuclei often attain 
monstrous dimensions, and sometimes break up into a large number of 
small nuclei. In the endosperm of the crown-imperial, transition-forms 
between direct and indirect fission in the smaller of these nuclei may 
be observed. The nuclei disappear, and the nuclear thread breaks up 
into a number of chromosomes ; without the nuclear membrane dissolving, 
or the formation of a nuclear plate, the nucleus becomes constricted 
across the middle, so that it becomes dumbbell-shaped. Similar modes 
of fission have been observed in animal cells. 
Nuclei of Lilium longiflorum.| — Mr. H. H. Dixon states that the 
chromosomes of the dividing nuclei in the growing point of the stem 
of this plant vary in number, the most usual being 16 or 24. 
Similar variations occur in the divisions in the pollen-mother-cells and 
in the upper nuclei of the embryo-sac. Before entering on the early 
stages of karyokinesis, the nucleus of the pollen-mother-cells possesses 
a very delicate and completely coiled nuclear thread. Even without 
impregnation the central portion of the embryo-sac becomes occupied by 
a large number of nuclei, which arise by direct division from the lower 
polar nucleus. 
Constituents of the Cell. J — Mr. J. E. Humphrey reviews the present 
state of our knowledge with respect to the minute structure of the 
vegetable cell. He regards the great variability and the evident passivity 
* Ann. Bot., ix. (1895) pp. 665-6; Proc. R. Irish Acad., iii. (1895) pp. 721-6 
(1 pi.). 
t Ann. Bot., ix. (1895) pp. 663-5; Proc. R. Irish Acad., iii. (1895) pp. 707-20 
(1 ph). % Ann. Bot., ix. (1895) pp. 561-79 (1 pi.). 
