NOTICES OF BOOKS. 153 
are seen to be formed of several threads, whose position of insertion is 
between the polar condensations of protoplasm and the two new nuclei 
forming from the separated portions of the nucleus-band (fig. 10), 
mass of protoplasm in the centre of the barrel-like mother-nucleus. 
Each of the two disk-like new nuclei travels towards one of the poles of 
the mother-nucleus, and unites when there with the polar condensation : 
the central collection of protoplasm becomes diffused over the parietal 
threads, after showing a faint tendency to aggregation in a direction 
parallel to that taken | by the nucleus-band (fig. mi Owing to expan- 
sion of the Ap rrel-like mother-nucleus, the parietal threads constantly 
ome more and more separated from one another, until they at last 
approach the layer of chlorophyll, raised, but not yet pierced by the 
rm 
plasm, to pierce the band of chlorophyll and become complete in the 
centre, and for the polar condensations to be evenly diffused over the 
new nuclei. Finally, the latter slowly assume a median position in 
their reapers © cells. 
endosperm-cells of oSiouiceee Ss are formed freely in 
the embryos by a poe ess essentially si gt mck a what we have seen 
in the corpusculum of Ephedra, a Prof. Strasburger has ascertained, 
y aid of reagents, that it is only when the eH Laas become suffi- 
ciently large to touch each other, that they are provided with a cellu- 
ose wall. the ; i 
nd. 
ging towards i s; this band divides, and the 
two portions sap t the opposite poles whic aus two 
nuclei are pro the of p on is secreted on a cell-band 
ic eee in the position formerly occupi y mnairided 
nucleus-band ; but if th ding nucleus does n 
t reac 
of its cell, the outside protoplasm is brought into use in the comple tion 
of the septum, Examination of many cases shows that this is the 
Cladophora, sr the nucleus is a ped e. More- 
wena: it is well-known t in a few rare cases the nucleus of the 
mother-cell takes no se in division, the new or being Bib 
ividing cell: this is re 
an instance of the nucleus having lost its power of segmentation, but 
the incapacity of the cell for division without the formation of 
masses of attraction. In eoson sense, the the or this last 
