110 BOTANICAL GAZETTE [FEBRUARY 
BISCHOFF (2) investigated a number of species and settled beyond 
a doubt the function of the sexual organs. His work was followed 
the next year by LINDENBERG’S monograph (20) which added little 
that was new. | | 
The study of the development of Riccia really begins with Hor- 
MEISTER (15), who gave an account of the development of the thallus, 
sexual organs, and fruit of Riccia glauca. 
Kny (19) made a careful study of the apical cells and the method 
of growth of the thallus. He did not secure plants developing from 
spores but used delicate thalli which had grown crowded together 
and did not bear sexual organs in the younger parts, so that the 
regular order of cells was not disturbed. He discovered the origin 
and manner of growth of the ventral scales and described the develop- 
ment of the sexual organs. Although HOoFMEISTER believed that 
young antheridia and archegonia could not be distinguished, Kny 
points out that they are distinct after the first walls are formed. 
LEITGEB (22) gives a complete account of the method of growth 
of the thallus in the Ricciaceae. His study of the sexual organs 
and fruit was in many cases incomplete on account of insufficient 
material. 
BIOLOGY OF RICCIA LUTESCENS. 
The account of the biology of Rzccza lutescens given here is based 
on field observations extending through two years, together with 
experiments and observations upon plants kept growing under 
favorable conditions in the greenhouse and laboratory. 
The first observations were made late in June. At that time 
the plants were growing upon the mud around the edges of ponds. 
Some of the thalli were very small and delicate, appearing merely as 
green specks on the mud, while others, which seemed to be older, had 
the ribbon-shaped form and thickened apical end already described 
(figs. 1-3). 
Material was collected and examined from time to time during 
the summer and autumn, with the expectation of finding plants 
bearing the sexual organs, because the statement is usually made 
that the species of Riccia fruit in summer and autumn when growing 
on the soil. The plants continued to grow well vegetatively through- 
out the summer, when they were in such a location that they were 
