and on the Structure of the Seed in the Rhamnacese. 85 



in which it is imbedded (even from over the chalaza), when it 

 thus appears in one unbroken pcripherical band, containing 

 spiral vessels : this separation of the raphe may be effected with- 

 out disturbing the under or more internal integument, showing 

 that it has no adhesion to it*. 



A very similar structure is found in Rhamnus utilis, Dene. : 

 here the embryo, the albumen, and the two integuments, are 

 folded on one another exactly as in R. ehlorophorus, the groove 

 being, in like manner, constantly on the same sinister margin ; 

 the testa also shows, on the dexter margin of the seed, a similar 

 continuous cord of the raphe ; but the intermediate integument, 

 in its plicature within the groov'e, adheres on both sides to the 

 inner tunic, till it arrives nearly at the bottom of the channel, 

 where it suddenly separates from it, and crosses the groove in 

 form of a diaphragm, leaving a vacant square space in the axis, 

 formed by a separation of the integuments, which extends from 

 the apex to the base, and upon this diaphragm is distinctly 

 seen the main cord of the raphe, — an organization similar to 

 to that of R. catharticus. The outer coating is of the same 

 fonn as in R. ehlorophorus, but of a different texture ; it has 

 the same longitudinal open slit along the lower half of the 

 sinister margin, but its edges are more or less inflected into 

 the groove. Its texture is not crustaceous, but consists of a 

 thick simple membrane, invested with a number of compact long 

 yellow cells, disposed horizontally, and aggregated into a lax 

 spongiose covering, which sometimes partially adheres to the 

 eudocarp. 



In Frangula vulgaris the structure is different from that of 

 Rhamnus, even when the raphe is lateral, as I have shown it to 

 be sometimes, in the latter genus. The seed is nearly orbicular 

 and much flattened; the crustaceous covering is as thin and 

 delicate as in Zizyphus, but its basal foramen is much larger, 

 rounder, and more open, with two thick callous lips placed right 

 and left of the ajis, not anterior and posterior, as in that 

 genus and in Colletia. Beneath it, and lying between it and 

 the intermediate integument, there is a deposit like charred 

 paper, which in most parts adheres to the external crust, but 

 is separable from it, as in Colletia. On removing this, we 

 find the very delicate intermediate membranaceous integu- 

 ment conical towards the base, where it terminates in a 

 hooked thread, as in Colletia, and from which, right and left, 

 along each margin, is seen a thick white cord, both arms 

 being joined in one pcripherical line over the apical chalaza. It 

 will be remarked that, upon the sinister side looking from the 



* Complete details of this organization will be given in plate 33 b of the 

 * Contributions to IJotanv.' 



