364 ON SOME REMARKABLE DEVIATIONS 



ment proceeds still further, and the pericarpium itself is 

 perforated by the embryo, which, while preserving its con- 

 nection with the parent plant, often attains the length of 

 from eighteen inches to two feet. This happens in 

 JRJiizopJiora and Briipiieirt, or the Mangroves properly so 

 called. In some of the spurious Mangroves, as Avicennia and 

 jEgiceras, a lesser degree of development takes place, and 

 in general their pericarpia remain entire till they have 

 dropped from the tree. In both cases the final cause of 

 149] the economy is sufficiently evident ; a greater than ordi- 

 nary evolution of the embryo being necessary to ensure its 

 vegetation in the unfavorable 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 

 Eufjenia, in which the integument of the seed is completely 

 absorbed before its separation from the parent plant, and 

 Avhile the pericarpium remains entire. 



An economy no less remarkable than that of the Man- 

 groves, but of a nature diametrically opposite, takes place 

 in the bulb-like seeds of certain liliaceous plants, especially 

 of Fajicratium, Crmum and Amari/Ilis ; 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, I 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 

 substance. 



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. But on a more careful inspection, of those seeds 

 at least in wdiich the separation precedes the visible forma- 

 tion of the embryo, I now find very distinct spiral vessels : 

 — these enter at the umbilicus, ramify in a regular manner 

 in the substance of the fleshy mass, and appear to have a 



' Prodr. rior. Nov. Holland, p. 297. 



