200 BOTANICAL GAZETTE [MARCH 
without in the end establishing any definite relationship with a 
specific group. The thing which does impress one, however, in 
looking over the work that has been done on Amentiferae, is the 
general resemblance to gymnosperms. Thus in working through 
the life history of such a form as Leitneria, one is constantly 
reminded of gymnosperms by one detail of structure or another. 
Thus, in the wood of Leitneria, one finds tracheae which show in 
every case an incomplete disappearance of the cross walls of the 
rather short cells of which they are composed, so that in section 
one sees clearly at the periphery of the vessel the remains of these 
walls. More striking than this incomplete disappearance of septa 
across the tracheae is the predominance of tracheids with bordered 
pits. 
As might be expected, it is in the study of the reproductive 
parts that one finds the most striking reminders of gymnosperm 
structure. Thus it is a relatively easy matter to imagine the 
derivation of a catkin from the compound strobilus found among 
gymnosperms. In either case the structure is made up of a series 
of bracts in whose axil stand sporophylls. In both gymnosperms 
and the Amentiferae the characteristic number of megasporophylls 
per bract is two, but it is in no way surprising to find this number 
occasionally reduced to one, as in Leitneria, while in the larger 
number of miscrosporophylls per bract we have a parallel among 
Gnetales, the only group of gymnosperms which has the compound 
staminate strobilus. 
Within the carpel the ovule also has several characters in which 
it resembles that of gymnosperms. Thus we find that it is a rela- 
tively massive structure, with a large development of nucellar 
tissue above the megaspore, so that the female gametophyte when 
it develops is deeply placed in tissue. 
Summary 
The microsporangium passes the winter in the spore mother 
cell stage. 
In the solitary ovule, the archesporial cell divides early; on 
January 21 there were two parietal cells above the single arche- 
sporial cell. 
