12 BOTANICAL GAZETTE [JANUARY 
but the different theories as to which type is primitive have not 
been reconciled. If, however, anomalous types of angiospermous 
embryo sacs are secondary and not primitive, as seems most 
reasonable, then the causes of these secondary modes of develop- 
ment should be investigated. This is obviously a problem present- 
ing serious difficulties, yet they are probably not insurmountable. 
A key to the situation may probably be found by considering the 
possibility that there is some relation between anomalous types 
of embryo sac development and peculiar environmental conditions. 
This has been suggested, for example, by JoHNSON (15). 
Since the strobilus theory of ARBER and PaRKIN (2) is based 
so largely on a comparison of the flower (euanthostrobilus) of 
angiosperms and the proanthostrobilus of the Bennettitales, we 
must refer to certain views as to the nature of these structures. 
ARBER and ParKIN, agreeing with HALiter (41) and SENN (26), 
consider the amphisporangiate flower of Magnolia and Liriodendron 
as made up of sporophylls and perianth borne directly on the main 
axis of the floral shoot rather than as a compound structure. This 
they regard as the most primitive type of angiospermous flower, 
reproducing the essential features of the Bennettitean strobilus. 
WETTSTEIN (31) and others, on the contrary, think that the primi- 
’ tive type is to be sought for among the monosporangiate Apetalae, 
and that the angiospermous fructification is a reduced inflorescence, 
derived from that of the gymnosperms. LicnreR (17), at least, 
interprets the Bennettitean strobilus also as a compound structure, 
an inflorescence. It is clear that conclusions as to the primitive- 
ness of different groups, as well as to the origin of angiosperms as 
a whole, will vary according to which of these views is accepted. 
The greatest differences between the two theories have been 
indicated. Whether the primitive angiospermous flower was 
anemophilous or entomophilous is perhaps of relatively minor 
importance, yet this question also is involved in both of these 
.theories. It would seem natural to imagine anemophily as the 
method of pollination among primitive angiosperms, yet if ento- 
mophily has played as important a réle as many suppose in their 
evolution, from their very origin, then the latter must be primitive a 
for this group. 
