ANATOMY AND PHYLOGENETIC POSITION OF BETULACEAE 42 1 
tive cells which reach the embryo-sac without disorganization and 
which nearly correspond to the binucleate generative cells of certain 
Gymno sperms. In this feature, therefore, they conclude that these 
species occupy an intermediate position between the Gymnosperms, 
iXi. which the male cytoplasm reaches the egg-cell, and the higher 
Angiosperms in which the male cytoplasm disorganizes in the pollen- 
tube and even in the pollen-grain. Hence they look upon the per- 
sistence of the male cytoplasm in Juglans as a primitive character 
retained from their gymnospermous ancestors; and, moreover, con- 
sider that the appearance of this character in chalazogams is significant 
and is a further proof of the great age of these plants. The tendency 
in seed plants to reduce the male gametes goes hand in hand with 
the evolution of the pollen-tube and seems correlated with its appear- 
ance. Such an opinion is the opposite of the one held by Van Tieghem 
(1868) in his work upon the floral anatomy of Juglans and the Coryleae. 
Nicoloff also (1904) came to an opposite conclusion from that of Van 
Tieghem and supported the views of Nawaschin. He considered the 
Betulaceae, as did Nawaschin, to be derived from the Coniferales 
while he would derive the Casuarinaceae from the Gnetales. Before 
discussing the above views let us note the opinion given by Coulter 
and Chamberlain (1903). Their position is one which does not bind 
them to either side. They state that none of the writers who regard 
the Amentiferae as derived from the Angiosperms with bisexual 
flowers suggest an affinity with any group of the Archichlamydeae 
but seem rather to incline to the author's opinion; namely, that 
whether they represent a single genetic stock or several, they appear 
to be isolated from the higher alliances. 
By means of the short account just given in regard to the evolu- 
tionary position of the Fagaceae and the Betulaceae, one may readily 
understand that from the study of the reproductive structures alone 
the situation has not been well cleared up. Perhaps the position 
taken by Coulter and Chamberlain is the one which it is safest to 
assume when the above field alone is taken into consideration. How- 
ever, some interesting facts may be pointed out from what has already 
been said concerning Casuarina. If, as appears to be the opinion of 
some, the Casuarinaceae are so closely aUied to the amentiferous type 
of plants as to be almost, if not quite, worthy of being placed with 
them instead of in a group by themselves, then how can the latter 
group be considered as one which has undergone any great reduction? 
