
182 DEVELOPMENT OF THE OVULUM 
I have only one observation to make further, with reference 
to the correspondence of the earliest stages of the ovulum, 
with those of the other parts of a flower. 
M. Mirbel has observed, Memoire 1, p. 7, pl. 1, fig. 2, 
that the amount of development varies even in the ovules 
of one placenta, but the extent in the instance cited would 
appear to be inconsiderable. 
In almost every case these correspond to a very eiii pe- 
riod of development of the ovarium, and a still earlier one 
of the corolla. And the only instance I know to the contrary 
is Stauntonia, in which casual observations lead me to infer 
that they correspond to the period of expansion of the flower. 
M. Brongniart mentions that in Corylus avellana, the ovula 
are not perceptible, even at the period of fecundation. 
[Memoire, p. 65, pl. 8, fig. 5, said to be taken from an 
ovary very young.] But this does not seem to be corro- 
borated by M. Mirbel. 
Instances are not wanting in which the ovule is actually 
absent before the completion of fecundation, at least such 
is my view of the structure of Viscum. 
phe. 
The vascular supplies of the ovule and seed, present them- 
selves under various aspects. In all cases they are suppos- 
ed to belong to the outer coat. In some instances their 
course is distinctly within the tegument, in some however, 
in which especially the nucleus adheres intimately to the 
tegument, the cord appears to run between the two, this is 
very evident in Cucurbitacez 
All ovula are aborigine, entirely cellular, conforming in this 
respect, to every other part of a vegetable when examined in 
` a sufficiently early stage, and instances are by no means un- 
common where such is the case in the matured seed ; and 
perhaps, incompletion until after fecundation, is the general 
ct. 
Further observations are wanted, to determine the exact 
period at which the vessels of the placenta, are prolong- 
ed into the ovule. 

