KARLING: GROWTH AND REPRODUCTION IN CHARA 479 
the tips were taken put out new branches after being pruned 
and grew rapidly. A few antheridia and cogent were present 
on the new growth on November 6. 
The temperature of the water of this culture was more 
constant than that of Culture A. The range of temperature 
extended between 16° and 25° C., and the variation within any 
24 hours was not over nine degrees, as shown in CHART I. This 
fairly low temperature appears to be the most favorable for con- 
tinuous growth of the plants. 
SERIES C 
Collected from park pond 245 ons eg March 26 
Grown in south windows 6). ck oes oe OO March 26-31 
Transferred to glass case reat ice in west window and grown under 
all-night electric illumination..................... March 31-May 7 
The plants of this culture were of the same lot as those of 
Culture B, collected at the same time and kept in a south window 
under the same conditions, On March 31 one jar with a control 
was transferred to a glass case in a west window where there 
_ was direct sunlight from 3 p. m. until sunset. The dimensions 
of the case were 50 X 60 X 100 cm. The sides and top were 
of thin clear glass that allowed full passage of light. Fifty pounds 
of ice was placed between the two jars each day. The tempera- 
ture did not go above 7° C. throughout the experiment, and on 
several days it ran down as low as 2° C. The illumination in 
the glass case in the early forenoon was about 25 foot-cafidles. 
Electric illumination was continuous throughout the night with 
the light bulb in the same position as in the preceding experi- 
ments. On April 15, seven days after the all-night illumination 
was begun, antheridia and oogonia appeared 
The vegetative growth in this case during the time of the 
experiment was hardly noticeable. There was no elongation 
of the internodes, and scarcely any new leaves were formed. 
The antheridia and oogonia grew slowly, and at the time of 
photographing, May 28, were only one-fourth full size. Fic. 
2, PLATE 12 shows a typical plant of this culture beside a control 
plant. The length of day for the period of this culture had 
increased about three hours and forty minutes beyond that for 
cultures 0 and A. Culture C was receiving several hours addi- 
tional daylight and correspondingly less electric illumination. 
