M. Benson. 
49 
This late addition of tracheides outside an exarch xylem-mass 
must be regarded as being of a secondary nature and probably 
representing secondary thickening, greatly reduced. Sometimes, 
though not constantly, indications of radial seriation are shown by 
the secondary tracheides or by the parenchyma outside the primary 
xylem; this fact acquires some little importance when taken in 
connection with the late differentiation of the peripheral tracheides. 
The fact that the secondary tracheides had not been previously 
recorded may be due to varietal" or individual variation in this 
respect, but more probably to the very tough cortex, which disposes 
one to examine the rhizome at a younger stage of development. 
A full account will be published later in the Annals of Botany. 
THE ORIGIN OF FLOWERING PLANTS. 
I N Mr. Seward’s letter on “The Origin of Flowering Plants” 
printed in the December number of the New Phytologist, 
the subject is referred to as one of the most fascinating of botanical 
problems. This must be my excuse for the present communication. 
Fossil Botany cannot be expected to indicate which forms first 
evolved the characteristic Angiospermic embryo sac. Hence so far 
as this character is concerned we cannot but look with interest on 
the facts revealed by Drs. Lotsy and Karsten. Gnetnni is now, I 
believe, generally recognized as possessing an embryo sac in which 
it is not difficult to conceive such an evolution may have taken 
place. But there is still the difficulty as to the origin of the 
Angiospermic flower. 
In spite of the fact that most of your readers have very 
probably considered and discarded the idea that Gnetnni can have 
anything akin to the ancestor of the Angiosperms in this respect, 
there is one suggestion as to the nature of its fructifications which I 
have never heard discussed and I should therefore be glad of any 
criticism on it. 
