270 BOTANICAL GAZETTE [MARCH 
from a more abundant collection. The axis was rhizomatous, giving off numer- 
ous roots at intervals, and bearing two kinds of leaves, one set of petioles being 
supplied by a monarch leaf trace, and the other set by a diarch trace. The 
smaller leaves, supplied by the monarch trace, show at base a sheathing organ 
which is thought to represent the so-called aphlebia of Zygopteris; if so, this 
is the first record of the structure in sae bade and further emphasizes the 
relationship of the two genera. BERTRAND’S view that the simple stele of 
B. antiqua is due to reduction and not to its Sie character is objected to. 
As the author says, “‘this view involves the assumption that the diarch type 
of petiole is older than the monarch, and the species (B. antigua) is in process 
of simplification. This result is not easy to harmonize with the fact that 
later forms of Boiryopteris petiole are triarch.”—J. M. C 
Origin of. transfusion tissue.—The so-called transfusion tissue of the 
leaves of gymnosperms has been recognized for many years as an anatomical 
feature of the group. WorspELL (1897) suggested, on the basis of distribution 
and nature, that it is a modified centripetal xylem. Since the presence of 
centripetal xylem is an important fact in discussing evolutionary sequences, 
this view extended the range of recognizable centripetal xylem. Now Miss 
CARTER* has studied the beginnings of this tissue in the cotyledons, using 13 
species, representing 9 genera of conifers. The conclusion is “that the first- 
formed transfusion tracheids appeared in such positions and were of such size 
as to make it appear improbable that they arose, in these organs at any rate, 
as an extension of the development of the centripetal wood.” The evidence 
from a comparison with the other elements of the vascular strand suggests 
that “transfusion tissue” develops from the parenchyma.— c. 
The causes of thorn development.—Since LorHe.ier conducted his 
researches on the experimental morphology of thorns, it has been generally 
believed that their development is favored and even caused by abundant light 
or by atmospheric desiccation. This was supposed to be the case particularly 
in the gorse, Ulex europaeus. ZEIDLER now calls these results in question, 
for he is able to secure the development of thorns in U/ex both in partial dark- 
ness and in moist atmosphere. He regards the leafy shoots secured by 
. LorHeELIER in moist air and in darkness merely as juvenile forms, whereas the 
thorny shoots are regarded as adult forms. It may be remarked that, even 
if further experiment should confirm the views of ZEIDLER, the real See 
is in no wise touched by his experiments. It would still remain to determ 
why “juvenile shoots” Benny appear at some times and “adult shoots” ow 
other times.—H. C, C 
32? CARTER, M. GERALDINE, A nn of the origin of “transfusion tissue.” 
Ann. whee 25°975-082. figs. 4. 
33 ZEIDLER, J., Ueber den eka ax a, und - MEE auf die 
Ausbildung ae Dornen von Ulex europaeus L. Flora 102:87-95. 
