The Structure and Development of the Ovule of 
Myrica Gale. 
BY 
EDITH MAY KERSHAW, M.Sc., 
Graduate Scholar in Botany in the University of Manchester. 
With Plate XXIV, and two Figures in the Text. 
I N view of the important peculiarities noted in the structure and develop- 
ment of the ovule of Casuarina and the Amentiferae, and of our 
rapidly extending knowledge of the seeds of the older Gymnosperms, 
it seems important that the ovules of allied orders such as the Myricaceae 
should be carefully examined, as so far only Myrica Lobbii had been 
examined in detail by Treub. 
When Treub 1 published in 1891 the account of his very thorough in- 
vestigation of the Casuarinaceae which had led to interesting discoveries, 
he suggested that this group should be placed in a separate subdivision 
of Angiosperms. In summing up his conclusion (p. 209), he says, ‘ Les 
Casuarinees occupent tres probablement par les phenomenes qui se passent 
dans leur nucelle avant la fecondation une place tout a fait exceptionnelle 
parmi les Angiospermes.’ These exceptional phenomena in the nucellus 
are — the considerable development of sporogenous tissue, composed of 
hundreds of cells — the great number of macrospores which develop, some- 
times twenty or more, — the entrance of the pollen-tube into the nucellus 
by the chalaza. ‘ Ce sont la autant de points cardinaux qui distinguent 
les Casuarina des autres Angiospermes’ (p. 215). 
From a comparative study of the Amentiferae, Juglandaceae, and 
Myricaceae which were considered as groups closely allied to the Casuari- 
naceae, Treub concluded that Casuarinaceae were the only group which 
showed these exceptional characters, and so he suggested a division of the 
Angiosperms into two classes : — 
Chalazogames — containing the family Casuarinaceae, and Porogames — 
containing the rest of the Angiosperms, the names being derived from the 
mode of entrance of the pollen-tube into the nucellus. 
1 Treub : Ann. du Jard. Bot. de Buitenzorg, vol. x, pp. 145-231. 
[Annals of Botany, Vol. XXIII. No. XCI. July, 1909.] 
