Notes on Recent Literature. 
235 
In the first place a detailed comparison is made of the sexual 
organs of the Archegoniatae with the gametangia of the Brown 
Algae. The wall of cells limiting the antheridia and archegonia 
and the canal cells of the latter are regarded as adaptations to 
terrestrial life. Proceeding to the reproductive organs of the 
spore-bearing generation, the spore-mother-cells of the archego- 
niate plants are compared with the unilocular sporangia of the 
Phaeophyceae and especially of the Dictyotaceae. While the 
essential correspondence of the tetrads in the two cases will readily 
be granted, it is not so easy to regard as necessary, or probable, 
the assumption that the structures corresponding to the sporangia 
of the Algae have become endogenous in the Archegoniatae. 
This is regarded as having taken place as an adaptation to terres¬ 
trial life. The archesporial layer in the moss-sporogonium is 
compared to a sorus of sporangia (such as are borne on the 
thallus of Padina ) become endogenous. This assumption leads 
to the amphithecial archesporium and the presence of a columella 
in Anthoceros being regarded as relatively primitive characters, a 
view against which serious objections could be urged. What are 
usually known as the sporangia of Pteridophyta are regarded as 
special appendages of the sporophyte enclosing numerous endogenous 
“ sporangia,” and Professor Schenck proposes to call the whole 
structure not a sporangium, but a spore-sac (Sporentheka). 
In the next section of the paper the gametophyte of the 
Archegoniatae is compared as regards form and organisation with 
that of the Brown Seaweeds. The points of comparison are all 
general ones such as distinction of a basal attaching region and the 
differentiation of the branches of the thallus. The most that can 
be concluded is that comparison of body-form and structure is easier 
between the Archegoniatae and the Brown Seaweeds than between 
them and other existing Algae. This criticism applies even more 
strongly to the comparison of the sporophyte of archegoniate 
plants with the thallus of the Phaeophyceae, and little weight can 
be attached to the parallel of foot and upper region in the embryo 
with the attaching disc and upper portion of the thallus in a Brown 
Seaweed. 
While the lack of any definite homologies between the gameto¬ 
phyte of the Archegoniatae and the thallus of the Brown Seaweeds 
is a serious difficulty in assuming a genetic connection between the 
groups, the absence of points of comparison between the free-living 
sporophyte of the Brown Algae and the sporophyte of the Arche¬ 
goniatae can be explained. This difficulty is met by considering the 
different and quite new conditions of development which affect the 
fertilised egg when retained in the archegonium. Professor Schenck 
does not consider this influence in great detail, but he states it very 
clearly, both in the introduction and in the portion of the paper 
dealing with the origin of the sporophyte. He shows also that the 
difference between the heteromorphous alternation of the Arche¬ 
goniatae and the homomorphous alternation of similar individuals 
in Dictyota finds its explanation in this factor. He further suggests 
that owing to this change in developmental condition of the egg the 
origin of the differences between sporophyte and gametophyte may 
have been sudden. The importance of this factor as bearing on the 
difficult problem presented by alternation of the heteromorphous 
