224 
H. F. Wernhant. 
with economy in ovule output as a leading tendency. The 
Apocynaceae terminate a longer branch (see annexed diagram), 
determined by specialization for seed-dispersal, by gynandry, and 
by reduction in ovule-number. Before the development of the last- 
named tendency a side-branch emerged from this apocynaceous 
line, the guiding principle of which was the further elaboration of 
the gynandrous tendency, coupled with aggregation of the pollen, 
thus producing the complexities of the Asclepiadaceae; in the latter, 
moreover, the specializations in fruit and seed foreshadowed in 
Apocynaceae—secondary apocarpy and comose seeds—have become 
practically constant characters. 
ASCLEPIADACEAE 
We shall regard the Gentianaceae as lying upon a third line 
emanating from the “ apocynal stock,” the determining tendencies 
being to the herbaceous habit, and to the unilocular condition of 
the ovary. 
