334 BOTANICAL GAZETTE [NOVEMBER 
Strasburger in Malva, but not in detail.?_ In this plant two nuclei 
were found in each cell. Guignard-also figured two nuclei in 
the tapetal cells of Lilium, and it now seems probable that the 
phenomenon is quite general, as Strasburger in the above cited 
work states. It was originally believed that these two nuclei 
were formed by direct division; but Strasburger*® has shown that 
this was really a process of fusion, and that the two nuclei were 
formed at an earlier date by the ordinary indirect method. 
In Convallaria, at the period just preceding synapsis, the 
already enlarged tapetal cells contain only one nucleus; but 
during synapsis, and even up to the first pollen-mother-cell divi- 
sion, the nuclei one by one divide by the mitotic method. Such 
spindles are seen in fig. 4. It is probable that every tapetal 
nucleus finally undergoes division, but this could not be accu- 
rately determined because of the subsequent fusion. The 
different stages in the fusion of these nuclei were sufficiently 
frequent after the first division of the pollen-mother cell (jig. 5): 
Cases could often be found even in anthers where tapetal spi 
dles also occurred. It is doubtful if all the pairs of nuclei fuse 
—in fact, it is probable that they do not, since many remain 
distinct even after the tapetum shows signs of disintegration. 
The wall of the mature anther in Convallaria presents no 
new features. It is composed of a conspicuous sae 
well-developed fibrous layer (endothecium) with beautiful spit 
markings, and the remains of the other wall layer (fig. 6). é 
remnant of the tapetum is now left. The time of disappearance 
of this structure was interesting because it occurred in some eget 
as early as the pollen-mother-cell stage, while in cae oi 
until after the pollen grains were mature. The time is seid 
the same even in anthers from the same bud. 
THE NUCLEUS OF THE ARCHESPORIUM. ae 
The very earliest stages of the archesporial nucleus oes 
vallaria differ only slightly in appearance from trite 7 ne 
nuclei ( fig. 7). The linin thread is exceedingly thin 2° 
7 Ueber den Bau und das Wachsthum der Zellhaute 89. 1882. 
*Theilungsvorgange der Zellkerne 99. 1882. 
