204 
CONTRIBUTIONS TO BOTANY. 
Figs. 1-7. 
I need not here recite the details of my own observations 
made in the spring of last year, upon the mode 
of growth of the anatropal ovule of Amygdalus^ •, 
suffice it to say that I have repeated them this 
year with the utmost care, from the very ear- 
liest periods of growth, and all that I had pre- 
viously remarked is fully confinned. I have no- 
ticed here, in every instance examined, as shown 
in the marginal figures, a deep depression 
completely upon one side (never at the extremity) 
of the wart-like pullulation from the placenta, 
which I have called the placentary sheath, because 
it encloses in its parenchyma the tracheal vessels 
of the future raphe, in the bottom of which 
hollow there is a small budding-point where the 
vessels terminate ; and out of this point the nu- 
cleus originates, standing in the bottom of the 
hollow : this nucleus soon becomes surrounded 
by the annular rudiment of the secundine, while 
the margin of the depression by degrees expands 
into a cup of a horse-shoe form, the two arms 
of which abut upon and embrace a lamellar plate 
of the placenta, and the opposite extremity is 
rounded into a concentric form, surrounding and 
including the nucleus and secundine. In Prunus 
the wart-like protuberance is more globular than 
in Amygdalus ; and upon one side, not far from 
the placenta to which it is attached, there is a 
very deep circular depression, in the bottom of 
which the diminutive nucleus is seen rising from 
the budding-point : this is gradually encircled 
by the secundine ; and the deeply hollow support 
becomes first a cup, which finally grows down- 
ward to form the primine, while its margin 
remains as the micropyle. Neither Mirbel’s 
view nor Fritsche^s notion is confirmed by 
my observations ; the many cases I have seen 
convince me that the early growth of the nucleus and secun- 
dine proceeds wholly from the budding-point or future chalaza, 
which is the point of termination of the tracheal vessels imbedded 
in the substance of the main support or placentary sheath. This 
mode of growth is most conformable to the ordinary law of de- 
velopment, and is quite analogous to the production of the sepals, 
petals, stamens, disk, and ovary from the budding-point of the 
* Ann. Nat. Hist. 3 ser. i. 359. 
