15 BOTANICAL GAZETTE [ocroBER 
in the cortex, which are of a very different size, but each is surrounded by a special 
and very plainly differentiated endodermis, in which the Casparyan spots are 
readily noticeable. The structure of the mestome strand in each is typical, and 
does not differ from that known so well from the Gramineae in general. The 
fact that the endodermis is differentiated at a very early stage, and that the 
inner cell walls become thickened long before the vessels and the adjoining tissues 
become lignified, makes this schizostelic structure plainly visible in the young 
rhizome, in the internodes, and partly also in the nodes. It would be interesting 
to know whether the structure is not to be found in other grasses.—THEO. HOLM. 
Morphology of Podostemaceae.—WENT?3 has made some remarkable obser- 
vations on the ovule of Podostemaceae. He has obtained abundant material 
and finds the several species studied very consistent with one another and very 
inconsistent with other Angiosperms, A future more extensive paper is promised, 
which will deal with all the features of the family. 
The outer integument develops first and forms the micropyle. Later the 
inner integument develops, but never incloses the embryo sac region of the 
nucellus, The hypodermal megaspore mother cell caps an axial row of cells, 
which first elongate and then disorganize, resulting in a pseudo-embryo 5a¢ 
inclosed by the inner integument. The true embryo sac enlarges but little, and 
the embryo grows into and occupies the pseudo-sac. After the first division of 
the megaspore nucleus, the primary antipodal nucleus degenerates promptly, 5° 
that there are no antipodal cells and no antipodal polar nucleus. he four 
micropylar nuclei form as usual, but the micropylar polar degenerates promptly, 
so that there is no “double fertilization” and no endosperm, It is to be regretted 
that alcoholic material and scattered stages did not permit absolute certainty oP 
many points.—J. M. C. 
Tracheae of ferns.—GwyNNE-VAUGHAN?+ has investigated the xylem of 
some of the recent ferns, and concludes that the current statement that the meta 
ston. The conclusions are that the xylem elements of pteridophy'*s as 
vessels with true perforations in their longitudinal as well as ™ 
bos niece hee continuous in the middle of the wall. It is probable 
: in 
oS *9 Weer, F. A. F. C., The development of the ovule, embryo 54¢ and ¢88 
ostemaceae. Recueil Tray. Bot. Néerland. 511-16. pl. I. 19 
A Lee anes D. T., On the real nature of the tracheae in the 
nnals of Botany 22°517-523. pl. 28. 1908. 
