IN FLOWERING PLANTS, 151 
It is scarcely necessary to repeat, that the determination 
of its situation is of primary importance, for it indicates the 
site of the future radicle. 
This, one of the most valuable practical rules in Botany, 
we owe to Mr. Smith, and Mr. Brown. 
Exceptions however occur to it in Ricinus and other in- 
stances, in the ripe seed. 
Further observations are therefore necessary. 
See Archives Pl. 12, p. 99. The drawings however do 
not satisfy me as to the body in which the embryo is deve- 
loped. Neither is there any explanation concerning the ra- 
phe, which would appear to be vascular. 
The Nucleus, Amande, Nucella, Tercine, and Quartine. 
[This organ, is of a much more important nature than either 
of the preceding, it is therefore much more universal. Iam 
of opinion however, that in certain Visca it is totally wanting, 
and strange as the above assertion may appear, I consider 
myself justified in adopting it from the consideration of 
Santalum. 
The nucleus is in almost every instance a cellular fleshy 
mass, occupying the centre of the ovulum, with the inte- 
guments of which it always agrees in direction. 
It has, if I may use the expression, a suigeneris appear- 
ance, so that to a practised eye it is at once recognised even 
when absolutely naked. : 
To the possibility of its being deprived of any tegument, 
Mr. Brown has alluded.] 
By its excavation, this organ, gives ríse to an additional 
coat, which may perhaps always be detached in the seed, 
except in those cases in which it adheres in the ovulum 
firmly to the tegument—on it Mr. Brown remarks—“ This 
third coat is formed by the proper membrane or cuticle of 
the nucleus, from whose substance in the unimpregnated 
ovulum it is never, I believe, separable, and at that period is 
