1910] BRIEFER ARTICLES 217 
collected. Cultures were made upon soil in porous clay pots, and in 
sterilized distilled water. 
Germination began in the soil cultures, four to six days after the spores 
were sown. Six weeks later, antheridia and archegonia appeared. As 
the genus Onoclea has been considered by most writers to be dioecious, it 
Was interesting to find monoecious prothallia occurring in about 1 yer 
cent. of the soil cultures; the other prothallia seemed regularly dioecious. 
The monoecious prothallia were of medium size, slightly heart-shaped, 
With a meristem bearing the archegonia; the antheridia, fewer in number 
than the archegonia, developed from the marginal cells. Some of the 
dioecious prothallia were large, heart-shaped, with a meristem bearing 
many archegonia; others were smaller, filamentous, slightly heart-shaped, 
or very irregularly shaped. These prothallia were one layer of cells in 
thickness, lacked a meristem, and the antheridia were formed both from 
the marginal and ventral cells. 
The development of the prothallia did not seem entirely influenced by 
their position, as indicated by PRANTL, for many of the smaller prothallia, 
the “‘ameristic” ones, were found in the less crowded regions; while the 
larger prothallia, the ‘‘meristic” ones, bearing only archegonia, were 
often found in the more crowded regions. 
An attempt was made to produce monoecious prothallia through the 
influence of an inorganic solution. For this purpose large, heart-shaped 
prothallia with archegonia in-various stages of development were selected 
and transferred from the soil to BEYERINCK’s solution. Four to seven days 
later, in one-half of the cultures examined, a number of monoecious pro- 
thallia were found, antheridia having developed from the marginal cells 
of the prothallia, near the notch. In all cases, death of the prothallia 
immediately followed, which seemed to be due in some cases to too long 
€xposure to direct sunlight, in others to injury of tissue in transferring ~ 
from the soil to the solution. 
Other cultures were transferred from the sterilized distilled water to 
solutions and kept in moderately weakened light. Two to four weeks later, 
in these cultures, the majority of the prothallia became monoecious; numer- 
Ous antheridia were produced, both from marginal cells and from the ventral 
surface cells on the sides, and near the apex of the prothallia. Other pro- 
thallia gave rise to numerous proliferations; some were mere filaments 
bearing antheridia at their apices; others had the thallus form, were dis- 
tinctly notched, and produced antheridia from the marginal and ventral 
surface cells. 
After all the prothallia needed for experimental purposes had been 
