470 BOTANICAL GAZETTE [DECEMBER 
what may have been originally sexual processes but which at present serve some 
peculiar and special function. 
Section V deals with cell activities at critical periods of ontogeny in plants. 
The literature is discussed under the headings, apogamy, apospory, hybridiza- 
tion, and xenia. Historical accounts are given, but most of the space is devoted 
to cytological papers of the last three or four years. About 150 papers are cited 
in the bibliography. Section VI, which concludes the series, is entitled “Com- 
parative morphology and physiology of the plant cell.” The material is treated 
under the heads: the simplest types of plant cells, comparisons of the structures 
of some higher types of plant cells with simpler conditions, some apparent ten- 
dencies in the evolution of mitotic phenomena, the essential structures of the 
plant cell and their behavior during ontogeny, and the balance of nuclear and 
cytoplasmic activities in the plant cell. 
The series as a whole contains a fuller treatment of the subject than that 
given in KorRNICKE’s recent paper, Der heutige Stand der pflanzlichen Zell- 
forschung.*8 The writer’s personal views are expressed freely throughout the 
work. The bibliography of recent literature is quite complete.—C. J. CHAM- 
BERLAIN. 
Lanc"? has studied the structure and development of Cyathodium, a tropical 
genus of Marchantiaceae. The few species occur in the deep shade of tropical 
forests, in dark caves, in the crevices of walls, or even on paths in more exposed 
positions. The two forms studied (C. foetidissimum Schifin. and C. cavernarum 
Kunze) were collected in the Malay Peninsula and the material was preserved in 
alcohol. One interesting feature of the investigation was that it made possible 
a comparison between one of the least reduced and the most reduced form in 
the genus. The antheridia are borne on small disk-shaped antheridiophores, 
developed from the lower surface of the thallus, and at maturity are essentially 
similar to those of other Marchantiaceae. LErTGEs’s surmise that the antheridial 
wall is not formed of a layer of cells was definitely set aside for both species. In 
both species the archegonia stand on the morphologically upper surface of the 
thallus, in C. cavernarum actually retaining this position, but in C. foetidissimum 
becoming displaced so as to appear to be borne upon the under surface. e 
development of the sporogonium in the main resembles that of other Marchan- 
tiaceae, the sporogenous tissue and the greater part of the wall of the capsule 
being derived from the epibasal cell, and the foot and the base of the capsule wall 
being derived from the hypobasal cell. The four cells at the base of the foot 
grow out into a number of relatively long tubular processes, each of which may 
branch once or oftener, thus greatly increasing the absorbent surface of the foot. 
The conclusion is reached that the supposed close relationship of the genus with 
Targionia is confirmed; and that it is probably a reduction group of species, 
18 See Bor. GAZETTE 39: 30-31. 1905. 
19 Lanc, Witiiam H., On the morphology of Cyathodium. Annals of Bot. 19: 
411-426. pls. 21-22. 1905. 
