42 DR. MARGARET BENSON, MISS E. SANDAY, AND MISS E. BERRIDGE ON 
Angiospermie embryo-sacs. The polar nuclei meet and fuse. The antipodals perish 
early, but can occasionally be shown to have formed walls around themselves. 
The embryo-sacs, including the fertile ones, produce long basiscopic cæca, along which 
the pollen-tube may or may not travel. Mr. Frye figures a case of triple fusion which 
is not quite convincing, owing to the fact that the presence of a pollen-tube is not 
demonstrated, and it is difficult to believe that it could have escaped notice if it had 
been present. Although further confirmation seems needed of the observation of triple 
fusion, there is no reason to doubt that it will be forthcoming. The egg-cell was in 
no case observed (by Mr. Frye) with a wall, and this is explained by the fact that 
fertilization had not been carried out, his material being too young for the culminating 
stages. This brings Casuarina into line with the normal case. ‘The clothed oospore 
rests while endosperm-development proceeds, and the segmentation of the embryo is 
perfectly normal. We have therefore. now a fairly complete story of the embryology 
of Casuarina. 
SUMMARY OF CHARACTERS IN WHICH CARPINUS AND CASUARINA AGREE, 
Both genera consist of arborescent, wind-fertilized species. Both are moncecious, 
with their flowers closely aggregated in unisexual catkins. 
The female flower in both is dimerous, bearing long free stigmas. In Casuarina it is 
borne singly in the axil of a bract, and itself bears two bracteoles. In Carpinus the 
terminal flower of the dichasium is abortive, but flowers are borne in the axils of its two 
bracteoles, and each itself bears a pair of bracteoles. Thus both genera come under 
Eiehler's type-form for the partial inflorescence for the Amentace *, orige differing 
from Carpinus exactly as Quercus differs from Fagus. 
The ovary in both genera is inserted in the radial plane. 
The absence of a perianth in the female flower of Casuarina is a character common 
to Betula and Alnus, and may be correlated with the later development of a wing from 
the periearp-wall, which occurs in all three genera. - 
In Carpinus no wing is developed from the pericarp, and hence the perianth — 
persists. 
The male flowers in Caswarina each consist of a single stamen; but this shows à 
marked tendency to bifurcate t, a tendency which is still more marked in the numerous 
stamens of the male flower in Carpinus. In neither case can we recognise any perianth, 
but bracteoles are present in both. 
To turn now to the faets of embryology as revealed by the researches of Treub and 
Frye on Casuarina, and by our work on Carpinus, as detailed in the former and present 
part of this communieation, we find that in both genera the ovary is originally bilocular 
and contains two anatropous, bitegumentary ovules 1. 
In both genera secondary fusions take place between the ovule and the placenta to 
* Eichler’s ‘ Blüthendiagramme, pp. 11—49, part 2. 
t Fig. 15 s in Engler’s ‘Pflanzenfamilien,’ Teil 3, Abt. 1, fails to indicate this fact. í 
+ Demonstrated in Carpinus by Miss Ewart, vide fig. 314 4, * Natural History of Plants ’ (Kerner, ed. by Oliver). 
