Cutting.—On Androgynous Receptacles in Marchantia . 355 
Discussion. 
The androgynous specimens of Marchantia described above differ 
from any androgynous fructifications yet described, in that the male portion 
not only arises from a branch after this branch has been definitely 
differentiated as female and has grown with the configuration of such and 
with a portion of its morphologically upper surface turned downwards, 
so that the morphologically upper surface of the male outgrowth is likewise 
turned downwards, but also is capable of continuing its growth and giving 
rise to a series of branches, resembling, in general outline, the arrangement 
seen in the asymmetric antheridiophores of some of the Marchantias, 
e. g. in M. chenopoda. In this respect it resembles a proliferation 1 of the 
tissues of the female branch rather than a replacement of it, and this 
suggestion is made even more likely when we remember that archegonia 
are usually, if not always, formed before the female branch gives rise to the 
male outgrowth. The distribution and number of the male outgrowths 
is irregular, agreeing in this respect with Dumortiera rather than with 
Preissia. 
Leitgeb was of opinion that the androgynous nature of his Preissia 
receptacles was due to a delaying of the sexual differentiation; granting 
this, the reason for the delay still remains to be discovered. The fact that 
a clump of thalli, probably derived from one or a few thalli by vegetative 
reproduction, was found by Leitgeb bearing androgynous receptacles, and 
that individual thalli selected from these continued to bear such in abun¬ 
dance the following year, strongly suggests that their formation does not 
depend on external conditions, but on the inherent nature of the thallus. 
Ernst reports that Dumortiera may bear male, female, and androgynous 
receptacles in any combinations, 2 but this does not negative the view given 
above, more especially as Preissia itself is often monoecious. It must also 
be remembered that in some of the monoecious species amongst the 
Marchantiales the male and female gametophores are borne quite close 
to each other, and yet androgynous receptacles have not been recorded 
in them. 
In the absence of living plants of the androgynous Marchantia it is not 
possible to decide whether the condition in this species is governed by ex¬ 
ternal or internal factors. It is very interesting, however, to find a bisexual 
species in a genus which has always been regarded as strictly dioecious. 
The experiments of Kny, in which the gemmae of Marchantia 
1 Similar vegetative proliferations have been noticed by Lindberg (13) in archegoniophores of 
Dumortiera , by Leitgeb (12) in those of Dumortiera and Marchantia , and by Okamura (16) in the 
antheridiophores of M. cuneiloba and M. geminata. 
2 I cannot find whether this is so in Preissia or not, but as it is often monoecious it would seem 
that this is very likely to be so. 
A a 2 
