310 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
CRYPTOGAMS. 
Pteridophyta. 
Vascular Anatomy of Angiopteris evecta. — Hugo L. Blomquist 
(Bot. Gaz ., 1922, 73, 181-99, 4 pis. and figs.). A developmental study, 
rendered necessary by the marked changes in the anatomical structure 
that arise from stage to stage of the plant’s growth leading up to the 
very complex structure in the mature Angiopteris. The most con- 
spicuous variations are : (1) elimination of endodermis ; (2) appearance 
of commissural and medullary strands of increasing importance in the 
central region ; (3) repeated bifurcation of leaf traces ; (4) point of 
attachment of the commissural strand and point of forking of the 
leaf trace become more closely situated to the central strand ; (5) varia- 
tion in place of attachment of root steles. Much of this variation tends 
to the breaking up of the central strand, a fact which points to a poly- 
stelic condition so characteristic of the phylogenetically advanced types 
of the different groups of vascular plants. The absence of cauline 
procambium and the definite relation between roots and leaves suggest 
that the vascular tissue of the central region is a sympodium of leaf 
traces, and most, if not all, of the central strand is of foliar origin. 
For the relative distribution of leaf traces, roots, commissural bands, 
etc., reference should be made to the author’s own summary. 
A. Gepp. 
Some Observations on Isoetes Drummondii A. Br. — T. G. B. 
Osborn {Annals of Bot., 1922, 36, 41-54, figs.). A study of tho 
biological morphology of this plant. (1) Isoetes Drummondii is widely 
distributed in South Australia, growing terrestrially in seasonal swamps 
during the winter rainfall. In the dry summer it aestivates, in common 
with the other geophytes of its association. (2) The stock is buried 
about 2 cm. deep, and during the vegetative season displays only a 
small rosette of linear leaves above the soil. (3) The stock is trilobed 
the projecting portion of each lobe is composed of caps, such caps being 
the whole of the leaf- and root-bearing portions of the stock developed 
in previous growing seasons. The abscission of such caps is a result of 
the regular alternation of growing and resting periods (during which 
there is great desiccation). (4) As the dry season approaches, the 
leaves dry up and become detached, leaving their tough bases and 
sporangia in situ upon the stock, wholly buried and invisible. (5) 
Early in the rainy season following, the hardened bases of the sporo- 
phylls are forced above the surface of the soil in a projectile -like mass, 
carrying with them the sporangia, by the expansion of certain pads of 
mucilage cells formed at the close of the previous vegetative season on 
the extreme bases of the sporophylls and from the superficial cells of the- 
leaf-bearing cortex. About the same time the leaves of the new vege- 
tative season begin to appear. (6) The imbricate mass of sporopbyll 
bases breaks up upon the surface of the soil, and the spores are set 
free by a tearing away of the sporangium wall from its attachment to 
the sporophyll when sodden. This is due to a difference between the: 
