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XII. On the Development of the e. and Elaters of Marchantia polymorpha. 
By ARTHUR Henrrey, Esq., F.R.S., F.L.S. Se. 
Read November 20, 1849. 
M. MIRBEL^*, in the first of his celebrated essays on the structure and development of 
Marchantia polymorpha, expresses himself in a note in the following terms:—* The ` 
origin of the elaters would, I think, be a curious discovery. I should not be astonished 
if most direct and positive observations led one day to the conclusion that these organs 
are but one of the numerous modifications which the utricles undergo. Such a result would 
decide many questions which we have long been endeavouring to solve.” 
In his second memoir on the same subjecti, he announced the fact that he had 
observed the development of these bodies from the utricles; and’ the progress of vegetable 
anatomy since that time has made it a matter of certainty, that all the forms of the 
elementary tissues are to be referred to a cellular type. But so far as I can discover, all 
observers, who have hitherto investigated the development of the spores and-elaters of the 
Hepatice, have overlooked certain important points. In the course of a series of observa- 
tions on the development of spores, made in reference to the theories of cell-development 
in general, my attention was strongly attracted to a very peculiar condition which I met 
with in the young sporangia of M. polymorpha, and as I can find no notice of the phe- 
nomena in the works of previous authors, I am induced to publish an account of them. _ 
The spores of Marchantia are produced, as is well known, in sporangia enclosed in 
peculiar receptacles or involucres situated at the base of the rays of the stellate body 
borne on the pedicel, on the under side. It is unnecessary to notice the characters pre- 
sented by the envelopes of the sporangia, as these have long since been well described 
and figured; the whole course of development of these parts is beautifully illustrated in 
the memoirs of M. Mirbel already referred to. 
The first indication of the production of the sporangia is the appearance of the organs 
called pistillidia, exactly resembling those of the other Hepatice and of the Mosses. 
Within the enlarged base of the pistillidium a small globule of a green colour is soon met 
with; this is the nascent sporangium, and in its subsequent development it enlarges 
within the expanding cavity of the pistillidium, acquiring a pyriform shape, and exhibit- 
ing at one period a little filamentous process at its apex. The nature or import of this 
process I cannot make out, but I found it also in Spherocarpus terrestris, and it is 
* Recherches PET et physiol. sur le Marchantia, &e., Mém. de l' Acad. Roy. des Sc. de l'Institut de France, 
vol. xiii, p. 337. 
. + Complém. des Observ. sur le Marchantia, &c. loc. cit. xiii. p. 375. 
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