SUMMARY OF CURRENT RESEARCHES RELATING TO 
division is irregular. The two anterior epibasal contents together give 
rise to the cotyledon ; and the apex of the stem is formed, not as in the 
leptosporangiate ferns, from one octant only, hut from hoth of the 
posterior epibasal octants ; the foot originates from the posterior pair of 
hypobasal octants beneath the stem ; the root is formed from an anterior 
hypobasal octant. The root-apex in the embryo contains a group of 
meristematic cells, instead of the single apical cell characteristic of 
leptosporangiate ferns. There is also no single apical cell from which 
all the later stem-tissue is derived. 
When the embryo has reached a certain size it bursts through the 
pro thallium, the root boring through below, while the cotyledon and 
stem grow through the upper surface. In this process Angiopteris is 
peculiar among those ferns whose embryogeny is known. The stipular 
structures characteristic of Marattiacese are absent from the first two 
leaves; the leaf-stalks are covered with hairs which contain a large 
quantity of tannin. 
Algse. 
Vegetable Growths as Evidence of the Purity or Impurity of 
Water * — Mr. A. W. Bennett discusses the value of the presence of 
vegetable growths in running streams as evidence of the purity or 
impurity of the water. His conclusion is that, in by far the greater 
number of cases, green living aquatic plants, whether phanerogamic Or 
cryptogamic, can have nothing but a favourable influence on the purity 
of the water by promoting its oxygenation. This is especially the case 
with the Cladophoraceae and the Conjugate. An exception occurs in 
the case of certain blue-green Algae or Proto phyta, Oscillaria, Anabsena , 
Rivularia , &c., which contain no chlorophyll in the ordinary sense of 
the word, and, in their decay, give out noxious and foetid gases, which 
render the water unfit for domestic purposes. 
Production of Zoospores. f — According to Prof. G. Klebs, the two 
phenomena of general growth and of non-sexual propagation in Algae are 
antagonistic to one another ; the same cell cannot perform the two 
functions at the same time. The production of zoospores is promoted, 
not by any single condition, but by the concurrence of a number ; and, 
under favourable conditions of light, temperature, moisture, and the 
chemical constitution of the medium, the production of zoospores may 
be brought about even in very young cells. 
Growth of Cladophora and Chaetomorpha.J — Herr L. Kolderup 
Rosenviuge states that the so-called coalescence of growth which 
frequently takes place between a main filament and its branch in these 
algae is not a true coalescence ; it originates from a gradual increase in 
length of the portion of the wall beneath the angle of the branch, which 
is common to the main axis and the branch. A very similar phenomenon 
occurs in Polysiphonia. A secondary coalescence of parts originally 
distinct may, however, take place. The prolification of cells of Clado- 
* St. Thom. Hosp. Reports, xx. (1892) pp. 51-8. Cf. this Journal, 1890, p. 489. 
t Arch. Sci. Phys. et Nat., xxviii. (1892) pp. 376-9. 
X Bot. Tidskr., xviii. (1892) pp. 29-58 (23 figs.). See Bot. Centralbl., li. (1892) 
p. 409. 
