6 
Review , 
initiating a subaeriai balancing mechanism ” (geotropism); 
starting a root system by the boring down into the organic debris 
of the substratum of the massive “ crampon system ” (sucli as we 
see to-day in Fucus and Tuvbinaria) with vestiges of the “ trichome 
system ” surviving as root hairs ; and a stele by lignification of the 
central cells of the axis, the peripheral “ phloem ” and secondary 
meristematic activity being already indicated among the massive 
brown seaweeds. This is all very well, but it is extraordinarily 
difficult to visualise exactly how, and by what stages it happened 
and the author gives us little help in this respect. 
In writing of reproductive structures in relation to the 
transmigration Mr. Church is particularly interesting. He regards 
the archegonium as “ clearly an end-product of oogamic evolution, 
the limiting term of something quite unknown, probably originating 
in something quite different from any recent archegonium, and, if 
we saw it, scarcely recognizable as such,” “ very probably of 
polyphyletic origin.” He points out that in so far as the 
archegonium is a means of obtaining fertilization in situ for an 
oosphere, whose post-sexual nutrition involves a parasitic diploid 
embryo, it shares these characters with the egg-bearing organs of 
Floridese, and hence such phenomena are part of the reproductive 
equipment evolved in the sea. The origin of the archegonium, as 
we actually know it, must therefore be sought in the transmigrant 
phyla, as a result of adaptation to the new conditions. But if, the 
author argues, fertilisation in situ had been developed during 
transmigration, the archegonial “ oospore ” would have been 
utilised as a resting phase, as happens in the transmigrants Cham , 
Vaucheria , etc., whereas in fact it always develops directly. 
The origin of the archegonium and of the antheridium he seeks 
in a multicellular branchlet of the algal body, represented in the 
Phaeophyceae by the “ multilocular ” gametangium, thus following 
the line indicated by B. M. Davis (1903), though Church insists on 
the importance of the distinction between the algal gametangium 
liberating autotrophic zoids and the antheridium of Archegoniates, 
whose zoids have to be fed as well as protected from desiccation 
during development. Added to this we have the further trans¬ 
migrant mechanism of dehiscence by turgescent terminal wall-cells 
on supply of free water. Church calls attention to the “ primitive ” 
features of the archegonium of Sphagnum , the most alga-like moss, 
and develops the analogy of the archegonium with the female 
organ of Chara f a transmigrant which tried to solve, with 
