316 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
layers of cells ; the walls entirely destitute of spiral, semi-annular, or 
other local thickenings. Elaters free, bi-spiral, acute or bluntly pointed. 
Spores minutely papillose. Involucel of the sporogone-foot well de- 
veloped. 
Exormotheca.* * * § — H. Graf zu Solms-Laubacli has studied in detail 
the structure of this little-known genus of Hepaticae from Madeira and 
Teneriffe, in which he includes also Myriorliynchus (Miccici) fimbriatus 
from Brazil, and corrects the descriptions of previous observers on several 
points. The systematic position of the genus he considers to be in 
the Marchantieae, nearest to Lunularia in the structure of the carpoce- 
phalum. It presents also analogies with the Corsinieae, and especially 
with Bosclria ; but the elaters are of quite normal structure. 
Algae. 
Structure and Multiplication of Pyrenoids in Algae.f— According 
to observations made by M. W. Chmilewskij, chiefly on Spirogyra, the 
pyrenoids of Algae multiply exclusively by division. The granules of 
the starch-envelope are not separated from the pyrenoid by chromato- 
pliore substance ; the two are in close apposition. The pyrenoid has 
a stellate form, its arms extending between the granules of the starch- 
envelope. This was observed also in other Conjugatae, in (Edogonium r 
Cladophora , and many Protococcaceae. After division of the nucleus 
and of the cell has taken place (in Zygnema), each daughter-cell con- 
tains a single chromatophore and pyrenoid. After about 1^ hours the 
chromatophore begins to divide centrifugally. The pyrenoid increases 
somewhat in size, and gradually divides, the nucleus becoming forced 
into the cavity thus formed in it ; and the starch-envelope divides into 
two. In a very few instances the division of the pyrenoid preceded 
that of the cell. The division of the pyrenoid is followed by a longi- 
tudinal splitting of the protoplasm filaments which radiate from the 
nucleus. In the zygotes the pyrenoids of the female chromatophores 
are still to be detected, their starch-envelopes not having entirely dis- 
appeared. 
Antherids of Taonia4 — M. C. Sauvageau describes the male organs 
of Taonia atomaria, which agree, in essential points, with those of 
Dictyota. The plants which bear antherids are distinguishable, even 
at a distance, from those which produce tetraspores. 
New African Genera of Freshwater Algae. §— In a paper on the 
Freshwater Algae of Africa, chiefly Angola, Messrs. W. and G. S. West 
describe a large number of new species, together with the following 
new genera : — 
Psephotaxus. Thallus subfilamentosus, epiphyticus ; fila brevissima, 
serie 3-7 cellularum formata, solitaria, subirregularia, et flexuosa, sim- 
plicia v. pseudoramosa, in muco firmo achroo nidulantia ; cellulae 
forinarum et magnitudinum variarum, subglobosae, ellipticae, oblongae 
* Bot. Ztg., Iv. (1897) l te Abt., pp. 1-16 (1 pi.). 
+ 10 pp., 1896 (Russian). See Bot. Centralbl., Ixix. (1897) p- 277. 
X Journ. de Bot. (Morot), xi. (1897) pp. 86-90 (1 fig.). 
§ Journ. of Bot., xsxv. (1897) pp. 1-7, 33-42, 71-89, 113-22, 172-83, 235-43 
(5 pis.). 
