|» from the usual Structure of Seeds. — 149 
 ciently evident; a greater than ordinary evolution of the em- 
bryo being necessary to ensure its vegetation in tle unfavourable 
circumstances in which it is unavoidably placed. 
But an analogous structure exists in other plants, where the 
' final cause is less apparent, as in certain species of Eugenia, in 
which the integument of the seed is completely absorbed. before 
its separation from the parent plant, and while the pericarpium 
remains entire. | 
An economy no less remarkable than that of the Mangroves, 
but of a nature diametrically opposite, takes place in the bulb- 
like seeds of certain liliaceous plants, especially of Pancratium, 
Crinum and Amaryllis; in some of whose species the seed separates 
from the plant, and even from the pericarpium, before the embryo 
becomes visible. ‘This observation respecting some of these seeds 
was, | believe, first made by Mr. Salisbury ; and in such as I have 
myself examined, I have found the fact connected with one no 
less interesting, namely, an unusual vascularity in the fleshy sub- 
stance. ! | 
- I have in another place*, in speaking of this substance, which 
constitutes the mass of the seed, and in a central cavity of which 
the future embryo is formed, stated it to be destitute of vessels, 
and entirely composed of cellular texture. Buton a more careful 
inspection, of those seeds at least in which the separation precedes 
the visible formation of the embryo, I now find very distinct spi- 
ral vessels :—these enter at the umbilicus, ramify in a regular. man- 
ner in the substance of the fleshy mass, and appear to have a cer- 
tain relation to the central cavity where the embryo is afterwards 
formed, and which, filled with a glairy fluid, is distinctly visible 
before the separation of the seed. It is a curious consequence of 
this tardy evolution of the embryo, which in some cases does not 
* Prodr. Flor. Nov, Holland, p. 297. 
become 
