472 MR. JOHN MIERS ON A NEW GENUS OF THE BURMANNIACEE. 
Myostoma, the mode of the fertilization of its ovules is more easily accounted for. This 
absence of stigmatic channels between the base of the style and the placentæ is far from 
a rare occurrence in phanerogamous plants; I pointed to it in the case of Ephedra, and 
quoted several authors who had observed the same circumstance in numerous other 
families*. 
Among these it may be especially noticed that Dr. Weddell, in his admirable memoir 
on the Urticeæ*, shows that the ovary is unilocular, and the ovule is attached by its funicle 
to the base of the cell, and that its mieropyle points upwards: here no channel of com- 
munication exists between the stigma and basal placenta, the stigmatic channels of the 
style terminating in the summit of the cell, where a tuft of tissue is seen similar to that 
described by Mr. Brown on the placentæ of Orchidee, and to which the expanded mouth 
of the outer coating of the ovule adheres with considerable tenacity; and he adds, “il 
n'est même pas rare de voir le tissu conducteur pénétrer dans l'exostome [micropyle] et 
lobturer complètement,” precisely in accordance with the observations of Mr. Brown. 
There is no mention anywhere of the descent of pollen-tubes to perform the act of 
fertilization. 
In corroboration of this, it may be mentioned that Dr. Hooker and Mr. Griffiths saw 
pollen-grains upon the stigma of Balanophora, but failed in tracing any transmission of 
pollen-tubes $; and I quote the words of the former (4. c. p. 17), showing that he could 
obtain no clue to the period when impregnation took place; nor could he trace any indi- 
cation of a chalaza, raphe, or foramen, at which “ impregnation is probably effected.” 
The want of an embryo in the seed would lead us to infer that in the nucleus of the 
Rhizogens there is no embryo-sac, in the ordinary acceptation of the term, and that the 
development of the ovule is different in its nature from that of Exogens and Endogens. 
We have as yet little knowledge on this subject; but in future investigations it must be 
remembered that in Myostoma the mouth of the external tunic of the ovule is never 
closed, that its funicle is tubuliform, and that it terminates in the mouth of that tunic, 
that there is no raphe, no vestige of a micropyle in its summit, or of a chalaza in the 
base of the inner integument. These very exceptional points of structure, by their 
influence upon functional development, would alone almost lead us to expect a difference 
in the organization of the seed. 
In this organization, as observed in Myostoma, and which seems to prevail generally 
in Rhizogens, are we to assume that an embryo is absolutely wanting, or can it be ? 
TY minute as to escape our means of observation? The latter view is not easily malt“ 
tained, because in all cases where a very small embryo exists it is enveloped in a Ye 
homogeneous large mass of albumen, composed of cells of great cohesion; but here ie 
* Ann. Nat. Hist. 3 ser. ix. 429: Contributions to Botany, ii. 146. 
+ Archiv. Mus. ix. 31, pl. 5. B. 4. 
t Dr. Hooker mentions, in a note (l. e. p. 17), that Hofmeister had observed a pollen-tube in the ovule of em 
eget i er Brown also n" ^ similar filament in the ovule of an Orchid, and showed that it was not a pollen-tube* 
daa wee T a 7 T coincides with that of the confervoid filament figured by Prof. Henfrey, which he v 
pee sine ular elongation t the embryo-sac of the ovule in Orchis (Linn. Trans. vol. xxi. tab. 2. fig. 41) 
is the same “ which Schleiden has certainly mistaken for a pollen-tube” (Joc. cit. p. 9)- 
and 
