, 252 MR. MIERS ON THE STRUCTURE OF THE SEED 
the seed, and to determine whether we are right in considering it to be an arillus, as 
doubts have been suggested on this subject by some eminent botanists. In the Clusiee, 
this consists of an entire coating, without the smallest fissure; it is fleshy, equal in sub- 
stance, not very thick, and generally of a reddish or orange colour. In the Tovomitee 
(at least I speak from observation in Tovomita and Commirhaa, and Póppig relates the 
same of Chrysochlamys), it is slit upon the dorsal face from top to bottom, with its fim- 
briated edges overlapping each other, so that when opened out, it appears like a flat sheet 
with the seed attached in its centre. In the Garciniee, the external coating is much 
thicker, of a more fluid and mucilaginous substance, generally edible, and quite entire, as 
in the Clusiee. Notwithstanding the different aspect and texture of this covering in the 
two last-mentioned tribes, its nature cannot there be questioned, and it is quite fair to 
conclude that the precisely analogous development in the C/usiec is, in like manner, a 
true arillus. It is, however, essential to determine this point beyond cavil, because in the 
Hypericine, Marcgraaviacee, and other orders, it has been held to be merely a thickened 
epidermis of the testa, while in the Magnoliacee it has been assumed to be the testa 
itself. In the latter family, where the seeds are generally suspended by long funicular 
threads, it forms a very conspicuous development, under the appearance of an entire, 
fleshy, scarlet-coloured covering, precisely similar to that of the Olusie@, and where in 
like manner within it, on one side, somewhat pressed into its soft substance, is seen pro- 
ceeding from the basal hilum to the apex a flattened raphe, the upper extremity of which 
is lost in a fungous spot filling the cavity of a distinct aperture pierced through the 
osseous shell,—a tunic which by most botanists has been regarded as the testa, but which, 
by some authorities, has been held to be the inner integument of the seed, called tegmen 
by Mirbel, and endopleura by DeCandolle. Endlicher was the first to suggest this idea, 
which he expresses in a very ambiguous manner; in his ‘Genera Plantarum,’ p. 837, he 
states that the seeds of the Magnoliacee have, in most cases, an external, fleshy, coloured 
integument covering a crustaceous festa, with its raphe situated between it and the testa, ` 
and terminated by a chalaza in its summit, but that sometimes there is no outer integu- 
ment, the raphe in such case being found between the ¢esta and endopleura. In this 
definition, Endlicher evidently designates by the term chalaza, the aperture in the sum- 
mit of thé Zesta, which I have called diapyle, and such misapplication of the term chalaza 
(a word, strictly speaking, confined to the peculiar thickening of the tegmen or inner 
integument, where it is connected with the raphe around the point in which all further 
trace of the continuity of the nourishing vessels ceases) has probably led to the error of 
considering the true festa to be the tegmen of the seed. In the diagnoses of the several 
genera of the Order (at least in the tribe Magnoliee), the first-mentioned character is 
assigned in detail to each genus in succession; but as the latter very inexact feature 
(where the raphe is found between the testa and inner integument) is applied to no single 
genus, it was probably meant to refer to the Z//iciec*, although this is nowhere explained 
or described. Dr. Asa Gray, however (in his ‘Genera Pl. Un. St.’ i. p. 60. pl. 23), adopts 
_ and amplifies this suggestion in unequivocal terms; stating that in Magnolia the seed is 
* On some future occasion I will state my observations upon th seeds ; i i 
f . 
em ssa: y ıpon the of Drymis, which present anomalous appear: 
