518 BOTANICAL GAZETTE [DECEMBER 
phyletic characters of the ferns can be estimated, the criterion of position of 
the nascent sorus may be held to take precedence, in point of early origin and 
constancy, over any soral characters except the primal features of the sporan- 
gium itself, and over any anatomical characters of the axis derivative from 
the protostele.” This is certainly an important conclusion, and in accordance 
with it, the leptosporangiate ferns (exclusive of the Osmundaceae) are grouped 
into two series: the “Superficiales,”’ in which the origin of the sorus is con- 
stantly from the leaf-surface; and the ““Marginales,”’ in which it is as constantly 
from the margin.—J. M. C. 
Morphology of Riccia.—Miss BLAcK® in a recent study of Riccia Frostii 
Aust. finds that this species is strictly dioicous and that the sex organs are 
scattered irregularly in acropetal succession. From the standpoint of the 
arrangement of sex organs, this indicates that R. Frostii is more primitive than 
R. natans, in which the antheridia are clustered in a disk, and the archegonia, 
which appear later, are usually in two rows. From the standpoint of restric- 
tion of antheridia and archegonia to different individuals, an advance beyond 
R. natans is clearly indicated. 
Miss BLACK agrees with Miss Hrrsu,‘ who also studied R. Frostii, that 
the air chambers are not produced by splitting of cell walls at the angles of the 
cells, but by papillate outgrowth. Unfortunately, the figure given, as was the 
case in the work of Miss Hirsu, does not show the earliest stage in the develop- 
ment of the chamber, but can as easily be cited as proof that air chambers 
arise by splitting at the angles of the cells of the dorsal layer. The youngest 
air chamber shown is too old to settle the question either way, but a study of 
the relation of cells in the figure indicates that possibly the chamber may have 
arisen by splitting of the dorsal layer. This splitting need not originally 
occur within the tissues as some recent writers assume, but may, as DEuTSCH 
showed in Targionia, extend from the surface inw: 
The rest of the investigation, which includes ft ets of sex organs, 
spermatogenesis, and sporogenesis, gives us nothing new.—W. J. G. LAND. 
Peripheral leaf cells.—In many leafy liverworts there is a marked differ- 
ence in form and markings of the peripheral cells of the leaf as compared with 
those farther away from the edge. GARJEANNE,* as the result of a study of 
10 genera, finds that the thickening of the peripheral cells is stronger if the 
plant is exposed to conditions which give great variation of water content; 
* Back, CaroLine A., The morphology of Riccia Frostii Aust. Ann. Botany 
27° 511-532. pls. 37, 38. 1913 
* Hirsw, Pavuwine E., The eesti of the air chambers of Ricciaceae. 
Bull. Torr. Bot. Club 27: 73-77. has. 6. 
ARJEANNE, A. J. M., Die a einiger Jungermannienblatter. 
a Flora 
10§:370~384. 1913. 
