MR. JOHN MIERS ON THE LOASACEA. 233 
in which case it would be an arilloid, certainly not an arillus, which is always an ema- 
nation from the chalaza: this view might be supported by the fact of the suspension of 
the inner body of the seed in Raphisanthe, and its attachment at the summit within 
the much larger capacity of the outer integument; but this supposition is again con- 
tradicted by the structure of the seed of Bartonia, where the inner body has no such 
organie connexion, either at the apical point of suspension or at the opposite extremity, 
Indeed, the whole seminal structure of the Loasacee offers an enigma which can only 
be solved by careful observations upon the living plants, by watching the successive 
growth of the ovules from their earliest stages, and tracing the channel through which 
nutrition is conveyed from the placenta for the secretion of the amniotic fluid, the growth 
of the albumen, and the perfection of the embryo. 
It may here be noticed, that Brown observed a similar anomaly in the integument of 
the seed in Orchidaceæ ; he showed (Linn. Trans. vol. xvi. 710) that it is entirely without 
vessels, and that the funicle at its origin is never vascular, being inserted in the ripe 
seed upon the outer integument, close to one side of its open foramen, and can hardly 
be traced beyond that point. It is singular that this great botanist should have al- 
lowed this anomaly to pass without pursuing it further; but he probably abstained from 
this, under the idea he once evidently entertained, that this outer tunic is an arillus 
(Prodr. 310). It is true that he afterwards traced the growth of this tunic from its 
earliest pullulation, and observed its gradual and anatropous expansion (Linn. Trans. vol. 
xvi. 710); he there described this tunic under the name of testa, and we may perhaps 
ascribe his reticence concerning the cause of so unusual an occurrence in the outer tunic, to 
his inability to discover the structure of the opake nucleus contained within it, the nature 
of which, owing to its minute size, has not yet been determined. Subsequently Prof. 
Henfrey (Linn. Trans, vol. xxi. plate 2) figured the gradual anatropous growth of the ovule 
m Orchis up to the period of its fertilization, and he there shows the absence of tracheal 
vessels in the funicle, as well as in both coats cf the ovule. I have noticed that in the 
ovary and capsule of Orchids there is an abundant supply of nourishing vessels, but they 
ire entirely confined within the lines of placentation. I have also shown a very similar 
structure of the seeds in Burmanniacee (Linn. Trans. vol. xvii. plate 38, fig. 4, and in 
Vol. xx. plate 15, fies. 17 & 18). 
In all the foregoing descriptions, the use of the terms usually given to the seminal in- 
eguments has been avoided, because, in these instances, they do not exhibit the features 
Which are universally regarded as necessary to the condition of testa and tegmen. 
In reference to what has hitherto been chronicled concerning the Loasacee, it may 
Temarked, that numerous species of Logsa and its congeners have been described 
n nies, but no one appears to have directed his attention to the peculiar organiza- 
PM n Integumental covering of their seeds; at least I can nowhere find any distinct, 
„ ^ either to the existence or absence of a raphe or chalaza in the seeds of that 
Y; the universal silence on that point tends to confirm what I have stated. In 
the systematic works of DeCandolle, Endlicher, Lindley, and others, it is merely said 
^ the ovules and seeds are anatropous, with the radicle in proximity to a vertical 
> Prof. Agardh is the only botanist who has made particular reference to this 
OL. Xxy, 2K 
