On the Prothallium and Embryo of Osmunda 
claytoniana, L., and O. cinnamomea, L. 
BY 
DOUGLAS HOUGHTON CAMPBELL. 
Professor of Botany, Leland Stanford ’ Junior , University , California , US. A. 
With Plates III, IV, V, and VI. 
dONG the various Pteridophytes that have been recently 
the subjects of investigation, the Osmundaceae have 
perhaps hardly received the attention they deserve, and this 
is especially the case in regard to the embryo. 
Finding that apparently no researches had been made upon 
the development of the embryo of Osmunda , the present work 
was undertaken in order to make a comparative study of this 
in two of the common American species, O. claytoniana and 
O. cinnamomea. During the course of the work, however, 
finding that many points in the development of the pro- 
thallium and sexual organs were only imperfectly described, 
and that the species under consideration showed numerous 
peculiarities, it was decided to study critically these points in 
both species, as well as the embryogeny. 
Both species are widely distributed throughout the north- 
eastern United States, and differ very much in appearance 
from the cosmopolitan O. regalis, which has been the species 
hitherto principally studied. While the sterile leaves of O. cin- 
namomea and O. claytoniana are much alike, the fertile leaves 
differ widely. In the former all the pinnae are fertile, while 
[Annals of Botany, Vol. VI. No. XXI. April, 1892.] 
E 
