OF THE RAPHE IN SEEDS. 105 
testa, and where the raphe terminates. Gærtner farther affirms that the amniotic fluid 
is secreted at this point of the gangylode, which is also the opinion of Mr. Brown (Linn. 
Trans. x. 37). This point is sometimes distinguished by a peculiar protuberance, within 
the cavity of the main body, which Mirbel calls the chalazal appendage (appendice chala- 
zienne), and he says that at this point the embryo-sac is first developed. We are indebted 
to Mr. Brown (Append. King's Voyage) for nearly all the information we now possess 
respecting the nature and origin of the several parts of the ovule, and the changes they 
undergo during the growth and perfection of the embryo, and it is impossible to estimate 
too highly the importance and merit of these admirable observations, the truth of which 
is unquestionable. A large share of credit is due to M. Brongniart, who about the same 
time, and to M. Mirbel, who three years afterwards, contributed many important facts on 
this subject, all confirming the previous observations of Mr. Brown. The latter able phy- 
siologist brought together all this information in his two celebrated memoirs “On the 
Development of the Ovule,” &c. (Mém. Acad. Sci. Paris, ix. p. 609 & 629): he there 
gives a regular nomenclature to the several parts of these developments, and reduces all the 
evidence into a beautiful system, which has been adopted by all, and which has remained 
unquestioned now for nearly thirty years; but true as it may be in a general point of 
view, the evidence I have now brought together will show that the laws considered so 
universal, fail in their application in many cases, perhaps in far more numerous instances 
than are here offered, or will at first be credited. The existence of the two outer tunics, 
the primine and secundine, had long been known; but their remarkably peculiar cupuliform 
shape, seen alone in a very young state, was first shown by Mirbel, and by him also the 
metamorphoses of the main body of the ovule, called ‘chorion’ by Malpighi, and ‘ nucleus’ 
by Mr. Brown, who first explained its functions, were now more fully demonstrated. 
Mirbel, who called this ‘nucleus’ the *tercine, showed that it is lined with a peculiar 
tissue, which sometimes becomes transformed into another tunic, the * quartine,’ and which 
in Statice he describes as forming a completely closed vesicle. Another body, which he 
denominates the ‘ quintine,’ is still farther developed in the interior of the quartine : this is 
the * sacculus colliquamenti’ of Malpighi, the ‘amniotic sac’ of Mr. Brown, the * embryo- 
sac” of M. Brongniart, the point of origin of which has been noticed above; when this 
vesicle is wanting, which perhaps more frequently happens, it is then the quartine that 
becomes resolved into the embryo-sac. According to Mirbel, one end of this sac is 
attached to the point of the gangylode, while the other is fixed to the summit of the 
tercine or quartine: it gradually swells from top to bottom, thrusting away the tissue 
q gr y : lei 
that surrounds it. Brongniart first noticed the fact of the descent of the boyaux of gm T 
grains, through the stigmatic channel, but failed in tracing their farther parga T 
s 4 . : e - » 
mode of their action in effecting the fertilization of th ovule, a discovery ges Fu - 
According to the observations of more recent physiologists, it pd Re å 
every case of fertilization of an ovule, the boyau of a pouce ve 8 
stigmatic channel, and is conveyed through the apical orifices of the primine and secun- 
i i i he tercine, thus reaches the embryo-sac, in 
. dine (the micropyle), and passing through t A ee : pm 
the na of which is a small globular body, called by Meyen ‘the primary utricle, 
which body, consequent on its osculation with the boyau, subsequently swells J becomes 
VOL, XXII. 
