Mottier.— The Embryology of some Anomalous Dicotyledons. 461 
Summary. 
Of the species investigated, all except Stylophorum diphyllum and 
Syndesmon thalictroides show a certain well-marked anomalous character in 
the development of the embryo of numerous individuals, while in others the 
anomaly may be only slightly manifested. In Stylophorum and Syndesmon 
the embryo is typically dicotyledonous, except in certain individual cases 
observed in which slight anomalies were present. 
In the anomalous forms in question, the primordium of the cotyledons 
arises as a thick crescent-shaped ridge of tissue, open at one side, growing 
out of the truncated end of the pear-shaped embryo. The opening of the 
crescent becomes the primary sinus of the cotyledons. With further growth, 
the primordium bifurcates at a point opposite the primary sinus and thus 
forms the two cotyledons. With subsequent growth of the embryo, the 
depth of the two sinuses may or may not become equalized. 
The anomalous character represents a derived and not a primitive 
condition. Consequently the anomalous Dicotyledons do not show that 
one class of Angiosperms was derived from the other. 
Literature. 
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