232 MR. JOHN MIERS ON THE LOASACEZÆ. 
I have been precise in the description of the seeds in all the foregoing genera, because 
of the uniformity in the want of a raphe in their seminal integuments, which is a feature 
of too remarkable a character to be passed over without special inquiry. By analogy, it 
must be presumed that at an early stage in the growth of the ovule, which in the Loasacee 
is certainly anatropous, some means must have existed for conveying the nutriment from 
the placenta to the base of the ovule, and for effecting, through the chalaza, the secretion 
of the amniotic fluid; for Mr. Robert Brown, the highest of all authorities on this 
subject, has shown* that the function of the chalaza is not only to assist in the nu- 
trition of the proper membranes of the seed, but for the higher purpose of secreting 
the amnios, the albumen being that portion of this fluid which remains after all the 
rest has been absorbed in the development of the embryo. He, as well as Mirbel, who 
followed in the same path, showed that in an atropous ovule there is no need of a raphe; 
but where the ovules are more or less anatropous (or, as they have been improperly 
termed, inverted +), the raphe becomes the essential channel for conveying nutrition 
from the placenta to the chalaza, and that it uniformly belongs to the outer integu- 
ment 1 ; hence it followed as a rule, that any external coating of an anatropous seed, void 
of araphe, must be of extraneous origin, derived generally from a growth of the placenta, 
or more rarely from an expansion of a caruncular swelling of the foramen of the outer 
proper integument, and is therefore in its nature arilloid. The enunciation of these facts 
as a general law, together with the disclosure of the circumstances under which the em- 
bryo-sac is evolved and fertilized, were rightly regarded as the most brilliant accession to 
our knowledge in modern times, and justly obtained for their great discoverer the high 
distinction of “ Botanicorum Princeps." 
Taking these facts into consideration, we must either suppose that in the original 
integuments of the ovule in the Lousacee a raphe once existed, which by some proces 
of absorption has disappeared, or we must imagine that the evolution and growth of the 
ovule must be effected by some other functional contrivance, yet unknown, different 
from the ordinary laws of development. "There is little in the appearance of the integu- 
ments to support the former supposition; for if we imagine the vascular cord to have 
disappeared, we certainly ought to perceive the vestiges of its course in the Irteg"* 
larity of the areoles in the reticulation of the outer coating, but no such irregularities 
vm be discerned. Under the second supposition, I confess my inability to form wed 
satisfactory conjecture; the only one that occurs to me is the possibility that, by som? 
kind of capillary action, the proper nutriment may be conveyed through the cells of D 
lax and scarcely aggregated tissue of the intermediate pellicular coating ; but this W° 
apply only to Caiophora, Blumenbachia, and a few others, but not to Gripidea, a 
the structure of the intermediate integument is very different. On the other hand, } 
might be imagined that the lax intermediate coating is the vestige of the original — 
tunie of the ovule, which has withered and become absorbed, while the outer 807 
integume a E 
3 : LS may Dave originated from an expansion of the foramen or of the place? 
* Linn. Trans, x, 35, 
i AT Development of the Vegetable Ovule, called Anatropous," Ann. Nat. Hist. 3rd scries, 
; 1 Gen. Rem. p. 59. 
iv. 19; Contr 
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