1908] CURRENT LITERATURE - 159 
dehisce, and spores germinate in the closed sporangia. As a result, dwarf male 
prothallia are produced, antheridia sometimes appearing at the three- or four- 
celled stage. Free spores under the same conditions never produce such pro- 
thallia, not having developed sexual organs at the conclusion of the experiment. 
The dwarf males do not burst through the wall of the sporangium, and ultimately 
die. It was found also that both free spores and those inclosed in sporangia ger- 
minate in.darkness. The suggested explanation of the formation of the dwarf 
male prothallia under the conditions described has no foundation in experimental 
work. It is to be hoped that the day of imaginary “explanations” is about 
over —J..M.C, 
Periodicity of algae—Brown?? has studied the appearance and disap- 
pearance of algae in selected ponds and streams in the vicinity of Bloomington, 
Indiana. In this region, an alga growing under ‘“‘steady normal conditions” 
remains in a healthy vegetative state throughout the year. A sudden change in 
external conditions checks this vegetative growth, and induces a resting stage or 
sexual reproduction. In reference to specific plants, Spirogyra nitida is the most 
abundant of the Conjugatae in the region studied, and S. varians is the most widely 
distributed alga, conjugating at all seasons of the year when exposed to har 
conditions (as the drying-up of a pond); Chaetophora thrives best in slightly 
Stagnant water at a temperature between 5° and 25° C.; Draparnaldia finds its 
La congenial conditions in flowing surface water between 1° and 15° C.— 
-M.C. 
Cytology of Synchytrium.—Griccs*° has continued an investigation on 
5: decipiens begun by F. L. Srevens, to whom he is indebted for material. There 
até 500 to 860 free nuclei in the cyst when cell walls begin to appear; but most of 
the Study was upon cysts with 100 to 300 free nuclei. While no centrosomes ws 
found in the metaphase and anaphase, in the telophase there are large asters with 
centrosomes at the center, whose origin has not yet been determined. As the 
nuclear vacuole forms about the chromosomes, the coarse rays of the aster bend 
about it and become transformed into the thick nuclear membrane characteristic 
of the senus. It is hoped that a further study will throw some light upon 
Systematic relations —CHARLES J. CHAMBERLAIN. 
Spo rangia of Lycopodiaceae.—As a result of her study of the apotang Ore 
"ing organs of the Lycopodiaceae, Miss Sykes" has arranged the different 
Ps tg of Lycopodium in a continuous series based on the shape and Te 
Wee the position of the sporangium, and the age a . eee 
See € evidence adduced seems scarcely sufficient to 
—e Harry B., Algal periodicity in certain ponds and streams. Bull. Torr 
- Club 35: 223-248, 1908 
Be aan Bos ium. Ohio Naturalist 8:277- 
286. pl. 20. 1908, T. F., On the cytology of Synchytrium. i | 
: SYKEs, M. G., Notes on th + ngium-bearing organs of the 
Lyco “) ph ] of t Pp rang 
wPotliaceae. New Phytol. 7: 41-60. pls. 2, 3. 1908. 
