360 BOTANICAL GAZETTE [APRIL 
chora) of the Dothideaceae, ee on the leaves of bamboo at OE 
alabar.—A. WEBER VAN Bosse (Ann. Jard. Bot. Buitenzorg II. 9: 25-33. 
1911) under the title “ nee sur ae genres nouveau d’algues de rota 
Malaisien” has published the following new genera: Bryobesia of the Chloro- 
phyceae, Mesospora of the Phaeophyceae, Exophyllum, Acanthochondria, 
Oligocladus, and Chalicostroma of the Florideae, and Perinema of uncertain 
relationship.—H. F. WERNHAM (Journ. Bot. 492346. 1911) adds another new 
species from Costa Rica to the genus Hamelia recently revised by the same 
author.—A. ZAHLBRUCKNER (Ann. K. K. Naturhist. Hofmus. Wien 24: 293- 
326. pls. 6, 7. 1911) in cooperation with several specialists under the title 
“Plantae Pentherianeae”’ has published a list of plants collected in South 
Africa by Dr. A. PENTHER; the article includes a new genus (Pentheriella 
ofim. & Musch. ) of the Compositae.—Different authors (Kew Bull. 1911: 343- 
348) have published several species of flowering plants new to science of which 
4 are from Mexico and South America.—J. M. GREENMAN 
Alternation of generations in Delesseria.—Alternation of generations 
among the red algae has begun to receive much attention, and a paper by 
SVEDELIuS” is one of the latest. The material for his investigation was col- 
lected at the Kristineberg Zoological Station, Bohnslin, Sweden, during 
November 1910. According to the account, in this species fertilization occurs 
in October, early in November the spermatangia are entirely washed off, tetra- 
spore formation occurs in November, and both tetraspores and cystocarps 
mature during December and January. The time of his collection, therefore, was 
too late for securing material for sperm-formation and fertilization, so that 
there is no description of the male individuals of Delesseria, or of the develop- 
ment of procarp and fertilization. 
The paper begins with an account of the development of tetrasporangia; 
then follow tetraspore formation, vegetative nuclear divisions in the tetra- 
sporic plants, and vegetative mitosis in the female plants. Finally there is 
discussed the problem of alternation of generations in the Florideae. The 
nucleus of the tetraspore mother cell undergoes the tetrad division, which is 
preceded by synapsis and diakinesis. In the diakinesis stage 20 bivalent 
chromosomes are present; after both heterotypic and homotypic divisions, 
tetraspores are produced with 20 chromosomes; the vegetative nucleus of the 
tetrasporic plants has 4o chromosomes; and the vegetative nucleus of the 
female plants has 20 chromosomes. In the resting nucleus there are present 
chromatin granules whose number is much higher than the double number of 
chromosomes. In vegetative divisions some of these chromatin granules 
directly unite with one another and form chromosomes, with no appearance of 
a spirem thread period. In the heterotypic division all chromatin granules 
t0 SVEDELIUS, N., Ueber den G t hsel bei Delesseria sanguinea. Svensk. 
Bot. Tidskr. 5:260-324. pls. 2, 3. figs. 16. 1911. 
