On the Development of the 
Leaf and Sporocarp in Marsilia quadrifolia 1 , L. 
BY 
DUNCAN S. JOHNSON. 
With Plates X, XI, and XII. 
LTHOUGH Marsilia and the related Pilularia have 
l\. been frequently studied during the present century, 
the exact origin and morphological significance of the 
sporocarp has never been satisfactorily made out in either 
genus, the chief reasons for this being apparently the com- 
plexity of the apical bud and the dense covering of trichomes 
over all the younger parts. The present work was under- 
taken at the suggestion of Dr. J. P. Lotsy, then of the Johns 
Hopkins University, in the hope that a detailed study of the 
development of the leaf and the sporocarp of Marsilia would 
give some indication of the morphological nature of the latter. 
The work has been carried on during the winters ’95-’96, 
’96-97, in the biological laboratory of the Johns Hopkins 
1 Accepted as a thesis for the Degree of Doctor of Philosophy by the Board 
of University Studies of the Johns Hopkins University, Baltimore, U.S.A., June, 
1897. 
[Annals of Botany, Vol. XII. No. XL VI. June, 1898.] 
K 
