176 
WALTER P. THOMPSON 
(b) The conditions in Gnetum throw little direct light on the 
problem of the Gymnospermic relationship of the Gnetales. Being 
in many respects the most speciaHzed member of the group, it pre- 
sents little evidence not already revealed in the case of Ephedra and 
Welwitschia. The evidence concerning the Gymnospermic relation- 
ship must naturally be sought in the most primitive member of the 
group, the genus Ephedra. That evidence has been presented from 
the gametophytic standpoint by Land (15, 16) and from the anatomical 
standpoint by the writer (27). From both fields it indicates definitely 
that the relationship is with the Coniferous Gymnosperms. It is, 
however, difficult to understand how the primitive bisporangiate 
Gnetalean flower can have been evolved from anything found in the 
Coniferales. But there is nothing found elsewhere in the Gymno- 
sperms which offers an easier solution of the origin of this flower. 
(c) In regard to the Angiospermic relationship it will be recalled 
that almost every structure described in the preceding pages shows 
some approach to the Angiospermic condition and that some struc- 
tures show conditions almost completely Angiospermic. The more 
important points are: the form of the inflorescence, particularly of the 
abnormal ones, the arrangement of the parts of the flower, the presence 
of an ovary with a style, the form of the stamen, the germination of 
the microspores at some distance from the nucellus, the behavior of 
the stalk cell, the free-nucleated embryo-sac and absence of arche- 
gonia, the organization of eggs, the fusion of nuclei preceding en- 
dosperm formation, the reduction in the number of endosperm pro- 
ducing cells, and the absence of free nuclear divisions in the proembryo. 
That the anatomy is just as clearly Angiospermic is evident from 
the possession of vessels, broad rays, and companion-cells in the bast. 
The habit of course is completely Angiospermic. Such a body of 
evidence can scarcely be ignored or put aside as the result of parallel 
development. Indeed in applying most of the contrasts ordinarily 
employed to distinguish Angiosperms from Gymnosperms, it is found 
that Gnetum would be classified with the higher group. Accordingly 
the sum of the evidence from all sides seems to lead to the conclusion 
that Angiosperms are phylogenetically related to Gnetales. This 
does not mean that any modern member of the Gnetales represents 
the type from which Angiosperms were derived but that the ancestors 
of Angiosperms were not far removed from the genus Gnetum. 
The only group of plants which rivals the Gnetales in the claim 
