IN FLOWERING PLANTS. 15s 
d’une masse parenchymateuse fixeé par une de ses extrémi- 
tés a la chalaze, libre ordinairement dans le reste de sa sur- 
face, et se terminant par un mamelon plus ou moins prolongé, 
qui correspond à la perforation des tégumens de I’ ovule, qui 
souvent s'engage dans ce trou et qui méme peut faire saillie 
au dehors." p. 81. 
The most important points of M. Brongniart's ideas res- 
pecting the nucleus, and which he says have quite escaped 
Mr. Brown, have not been corroborated by M. Mirbel, nor 
do my own observations, at all coincide with his. 
He says that the embryonary sac exists before fecundation, 
and that even at this period its communication with the cha- 
laza may have been effected, and to such a degree may this 
evolution take place, that even at the period above alluded 
to, the nucleus may be reduced to be a thin membrane. 
M. Brongniart describes a communication, which from his 
hypothesis regarding fecundation, would be necessary, be- 
tween the embryonary sac and the apex of the nucleus, and 
to render this required communication still more efficient, 
this tube is represented as projecting in many cases beyond 
the apex of the nucleus (p. 98) ; and subsequently, he thinks, 
that this exsertion takes place in all plants at the time of 
fecundation. | 
'The instance cited by this distinguished author, in which 
this tube is most conspicuous, is in certain Cucurbitacez, 
and in this he would appear to be confirmed by M. Mirbel, 
see his figure of C. anguria. Of the existence of a tube pro- 
jecting beyond the apex of the nucleus, I am aware of several 
instances, particularly in Cucurbitacee, and Asclepiadez 
but I have never been able to ascertain its communication 
with the embryonary sac, except in Santalum, in which it 
is a prolongation of the sac in question. 
The description of the tube given by Brongniart accords 
well with what is now known of boyaux, with the exception 
that Brongniart figures it as closed at its exserted end, and 
x 
