242 
CONTRIBtTTIONS TO BOTANY. 
to the organization I have described in the seeds of Cucurbi- 
tacecE* * * § . 
This singular extension and displacement of the raphe, ac- 
companied by the formation of an extraneous crustaceous cover- 
ing in the seed, is not altogether a novel fact, as I thought 
when I first remarked it in the CucurbitacecE ; for the occurrence 
was partly noticed thirty years ago, in Rhamnus, by Brongniart, 
who, strangely enough, was not struck by the appearance of so 
remarkable a phsenomenon, which he passed over without com- 
ment, and it has remained unnoticed by other botanists since 
that time. Brongniart’s words are worthy of being quoted, as 
showing a notable correspondence mth my observations. Al- 
luding to the RhamnacecB, he says f : “ Dans toutes ces plantes, 
le test lui-meme, examine au microscope sur des ovules dejh 
fecondes et h moitie de leur developpement, est compose de trois 
couches tres difiierentes ; Tune, externe, n^est qu’un epidermis 
mince J ; I'autre, moyenne, est solide et fibreuse, formee de fibres 
ou cellules alongees transversales, c’est elle qui doit former le 
test de la graine ; enfin Finterne, tres epaisse dans les premiers 
temps qui suivent la fecondation, est formee de parenchyme 
lache, compose de cellules remplies de globules verts; elle 
s’atrophie, peu-k-peu, h mesure que I’amande et Pembryon se 
developpent. C^est en general dans cette couche que passent 
les vaisseaux nourriciers, qui composent le raphe, et vont former 
la chalaze, raphe qui, dans ce cas, suit Tun des cotes de Tovule 
en dedans du test, et redescend en partie de V autre cote, apres 
que la plupart des vaisseaux qui le composent, ont donnes nais- 
sance par leur epanouissement k la chalaze.” The latter conclu- 
sion appears, however, to have been only conjectural §. 
The entire peripherical circuit of the tracheal vessels in one 
of the integuments of the seed, which I have invariably found in 
one unbroken continuity, was therefore not fully traced by that 
eminent botanist, although it is evident, from the above quota- 
tion, that he had noticed the return of the raphe over the cha- 
laza, and its partial descent down the contrary face of the seed. 
It is strange that this remarkable and novel feature was not 
afterwards alluded to, and that the mention of this extension of 
the tracheal vessels is omitted in the very copious diagnosis he 
• Linn. Trans, xxii. 92. f Ann. Sc. Nat. x. 340. 
t This is a thin layer of cellular tissue that invariably hues the epicarp, 
and partially adheres to the outer crustaceous coating of the seed in 
Rhamnus, and which I have not considered it necessary to mention in the 
preceding description. 
§ “ La chalaze vasculaire m’a toujours paru formee entierement par une 
^pauouissel^nt des vraies trachees : elle est formee exterieurement par 
une expansion des vaisseaux du raphe” {1. c. p. 341). 
