SUMMARY OF CURRENT RESEARCHES RELATING TO 
Tuomeya fluviatilis.* * * § — Air. W. A. Setcbell describes the structure 
and development of Tuomeya fluviatilis Harv. ( Baileya amerieana Ktz.) 
which, both in its vegetative organs and its mode of fertilization, forms 
a connecting link between Lemanea and Batrachospermum. Young 
plants put out filaments resembling the Chantransia form of Batracho- 
spermum. The antherids are developed from the terminal cells of the 
antheridial branches, and each produces a single antherozoid, which 
moves about for a short time with an amoeboid motion, but soon 
becomes spherical and motionless. The carpogonial branches become 
at length spiral, and the procarps are formed from their terminal cells. 
The contents of the antherozoids enter the trichogyne through an 
opening in its wall; and the trichophore then produces chains of 
carpospores resembling those of Batrachospermum. 
Structure of Zonaria.t — Mr. H. M. Richards describes the structure 
and development of the thallus of Zonaria variegata from Bermuda. It 
grows by the division of a marginal row of brick-shaped cells, and 
consists, in its most fully developed parts, of from five to nine layers of 
large medullary and two layers of cortical cells. Each initial cell of 
the superficial layers is soon divided into a large number of small cells. 
The concentric lines which are so conspicuous on the thallus are caused 
by some of the cortical cells overlapping others towards the margin of 
the thallus, the overlapping portion having a length of several cells. 
The author records an abnormal division of the contents of tetra- 
sporanges of Bictyota ciliata , by which they break up into an indefinite 
number of parts. 
Chlorophyll-bands in the Zygote of Spirogyra.i — According to 
observations made by Herr Y. Chmielevsky on several species of Spiro- 
gyra and Bhynehonema, no coalescence takes place in the zygote 
(zygosperm) between the chlorophyll-bands of the male and those of 
the female cell ; those of the latter always exhibit a more regular spiral 
than those of the former. After coalescence has taken place the female 
band always retains its green colour, while the male band becomes 
yellow, and gradually breaks up and becomes disorganized, being finally 
absorbed into the protoplasm of the cell-sap. In lateral conjugation the 
male band which disappears always lies nearer to the conjugating canal. 
When the zygote germinates after its period of rest, it always contains 
only a single nucleus, the result of the coalescence of the nuclei of the 
male and female cells, and a varying number of chlorophyll-bands, but 
always the same number as those in the female cell before conjugation, 
which remain unchanged in the zygote. 
Germination of Closterium and Cosmarium.§ — Herr H. Klebahn 
describes the structure and mode of germination of the zygote in species 
belonging to these two genera of desmids. 
In Closterium the four chromatophores resulting from the conjugation 
of the two gametes remain for a time distinct, subsequently uniting into 
* Proc. Amer. Acad. Arts and Sci., xxv. (1890) pp. 53-68 (1 pi.). See Bot. 
Centralbl., xliv. (1890) p. 81. 
t Pioc. Amer. Acad. Arts and Sci., xxv. (1890) pp. 83-92 (1 pi.). See Bot. 
CentralVL, 1891. Beih. 1, p. 5. % Bot. Ztg., xlviii. (1890) pp. 773-S0 (1 pi.). 
§ Jahrb. f. Wiss. Bot. (Pringsheim), xxii. (1890) pp. 415-43 (2 pis). 
