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PRIMITIVE 
STOCK 
Fic. 300.—Family tree of Ranunculacez, illustrating the evolution of the 
group as provisionally suggested in the text (pp. 437-440). 
into one plane, is shown in Fig. 300. If our idea of the kinship of 
the different genera be correct, this diagram represents the branch- 
ing lines along which we may suppose these members of the family 
to have evolved. All that lies below the terminal twigs is supposed 
to be buried; and, in a general way, the further a branch or line of 
descent extends to the right the more is it supposed to depart from 
the original ancestral form. 
Our vertical diagram thus indicates that of all the living forms 
of Ranunculacee, Caltha most nearly resembles the ancestor of the 
family. According to this view the story of the family’s evolution 
would be somewhat as follows. Among the descendants of Caltha- 
like moisture-loving plants which grew in a remote geologic age, 
some retained for innumerable generations the characteristics 
which fitted them for living under the comparatively uniform con- 
ditions afforded by protected moist situations, and are represented 
to-day by our marsh-marigolds. In these have survived a most 
primitive type of flower, hypogynous, with many-ovuled, distinct 
