STEIL: SOME NEW CASES OF APOGAMY IN FERNS 103 
The conical or cylindrical processes already described grew 
considerably in length when the cultures were placed in weak 
light. In such instances an apical cell could be readily distin- 
guished. The embryo in these cultures was frequently formed on 
the process, and usually it was produced as a direct outgrowth of 
the apical notch. The ‘‘light’’ area, or pale portion of the pro- 
thallium where the embryo begins its development, remains more 
conspicuous under these conditions. The colorless plastids, 
present in large numbers in the cells of the pale region, become 
chloroplasts under favorable conditions of light, and hence the 
nearly colorless region is not so clearly differentiated in the latter 
case. 
ATTEMPT TO INDUCE APOGAMY IN OSMUNDA REGALIS 
In the latter part of July, 1912, a large number of prothallia of 
Osmunda regalis were found by the writer in a swamp in the vicinity 
of Madison. Most of the prothallia at this time were small but 
had produced numerous antheridia. Some of the prothallia were 
removed with a depth of about three inches of soil and placed under 
bell jars in the university greenhouse. Several cultures were kept 
in a Wardian case where the illumination was very favorable for 
the normal development of the prothallia. Other prothallia 
were placed under bell jars and in different parts of the greenhouse 
where strong light was obtained for the greater part of the year. 
The latter were watered only from below and great care was exer- 
cised to prevent condensation of moisture on the prothallia. In 
this manner fertilization was prevented for nearly a year and a 
half. During this period, however, the prothallia grew to a large 
size, and numerous antheridia and archegonia were produced. 
Many of the prothallia reached a length of three centimeters. 
On such prothallia most of the archegonia were formed in acropetal 
succession, but frequently a number were produced among the 
older archegonia. In one instance the archegonia on one side of 
the “midrib” of a prothallium, measuring two centimeters in 
length, were counted and approximately five hundred were found 
to be present. Therefore this prothallium had produced about 
one thousand archegonia. 
When the prothallia were freely watered, embryos were pro- 
. 
