THE ORIGIN OF ANGIOSPERMS. 73 
agreement with Hallier " and Bessey f among others, though the contrary 
view has been recently upheld by Coulter and Chamberlain {. In our 
opinion, the similarity to be found between the general structure of the 
amphisporangiate strobili of both Monocotyledons and Dicotyledons, especially 
in those cases which we regard as preserving primitive features, and the 
general identity exhibited by the gametophytes, is almost conclusive in this 
respect. The supposition that such resemblances are due to homoplasy, as 
‘oulter and Chamberlain assert, does not appeal to us, for the chances of 
such complete parallelism of long duration must be almost infinitely small. 
Some evidence also has been recently brought forward to show that the 
polycotylous embryo may have been derived from a dicotyledonous ancestor, 
by the splitting of the two seed-leaves $. This, in conjunction with the fact 
that Bennettites, as also Ginkgo and living Cycads, possess two cotyledons, 
inclines us to the view that the dicotylous condition was a primitive feature 
of the great majority, if not all Spermophyta. 
ENTOMOPHILY. 
We have already indicated that, on our view, it was a radical change in the 
method of cross-fertilisation which called the Angiosperms into existence. 
It is not perhaps safe to assume that the Bennettitez, or still more the 
Hemiangiospermez, were wholly anemophilous, though we think there is a 
strong probability that such was the general method of pollination. At first 
we may imagine that such insects as visited the Mesozoie ancestors would 
be attracted to the male sporophylls for the sake of the pollen. In such 
amphisporangiate strobili as those of the Hemiangiosperms, cross-fertilisation 
would be likely to result occasionally through insect visitors, owing to the 
close proximity of male and female sporophylls. In a monosporangiate 
strobilus, however, the male cones would probably alone be visited, hence 
there would be no tendency to cross-fertilisation. Consequently the evolution 
of entomophily may be expected to have arisen in anthostrobiloid plants. 
In the case of the Angiosperms such primitive entomophily was preserved, 
and rendered permanent by a transference of the pollen-collecting mechanism 
from the ovule itself to the carpel ог megasporophyll, and by the closure of 
this organ. 
Such a view is in accordance with that expressed by Robertson |. The 
question, however, remains as to why this change in the manner of fertili- 
sation should have necessitated the infolding and union of the carpels. 
Robertson has recently asked this question, at the same time pointing out 
that a single ovule could hardly be pollinated any better, and that more than 
one could not be fertilised as well by the anemophilous method. It might, 
* Hallier (1901?, 1905). * Bessey (1897). 
1 Coulter & Chamberlain (1904) p. 283. $ Hill & de Fraine (1906). 
|| Robertson (1904). 
