KARLING: GROWTH AND REPRODUCTION IN CHARA 483 
On May 12 Culture E was removed from the dark room to 
an east window in the laboratory. There it continued to grow 
slowly all summer, producing numerous antheridia and oogonia 
on the new growth. By September 12 the plants were about 
-75 meter in length. The culture was transferred to a clean jar 
on that date; and from that time to November 6 it grew steadily, 
until the plants were curled around in the jar several times. 
Antheridia and oogonia were abundant on all plants. 
SERIES F 
Collected in park pond. ...2 sou Set ae Mla pera, March 26 
Grown in full sunlight in a greenhouse at 22°-25° C.....March 26-May 18 
Grown in full sunlight in a greenhouse..................-. May 18-Nov. 6 
Since the response of Chara fragilis to increased periods of 
illumination in the laboratory was so direct, a series of cultures 
was run to determine the results of growing cultures in battery 
jars in a greenhouse where the plants would receive sunlight 
from sunrise to sunset during the spring months. On March 
26, six large cultures with approximately 200 plants in each jar 
were started in a room in a greenhouse on which the direct 
rays of the sun fell the greater part of the day. The plants began 
to grow vigorously as soon as they were planted, but considerable 
difficulty was encountered in preventing them from being over- 
run by algae. The cultures were cleaned, and fresh water added 
several times, but by the end of May all but three of the cultures 
were dead. In the meantime, antheridia and oogonia appeared 
in the three remaining cultures on April 22. The length of day, 
reckoned from sunrise to sunset, at the time of fruiting was 
thirteen hours and fifty-five minutes. The temperature in the 
greenhouse in which Series F was grown was fairly constant and 
high. The variation was between 22° and 25° C. The growth 
at this temperature is rapid, but the plants become very slender 
and deteriorate in a short time. Fic. 1, PLATE 13 shows the 
variation of fruiting in different plants in these cultures on 
av 18. 
On May 18, the three cultures were removed to a room with 
lower temperature. The plants continued to grow and fruit 
vigorously throughout the summer, and by September 12 some 
of the plants were.75 meter in length, with antheridia and oogonia 
in as many as six whorls of leaves. A large number of mature 
oospores were present on the plants. On September 12 the 
