474 KARLING: GROWTH AND REPRODUCTION IN CHARA 
SERIES 0, CULTURE 0-3 
Di ssn a eb Le Viele, 8 bho he 1922 
ROS AE ois a og wk en bea es ey 50 1922 to Jan. 22, 1924 
Grown in greenhouse under all-night electric illumination. Jan, 22 to April 23 
Grown in north window of laboratory with only daylight cemapeets 
ril 23 to Nov. 6 
Series 0, Culture 0-1 consisted of three jars sath a control. 
The plants were brought from the field on October 18 and 
grown outside on an east window-sill. The plants were there 
subject to alternate chilling and warming as the weather changed. 
On bright days the morning sunlight fell directly on the cultures. 
The plants were green and healthy but grew slowly. They had 
increased about three inches in length when on January II the 
culture was placed on a shelf inside of the window under electric 
illumination during the night. A more vigorous growth was 
immediately evident. The internodes increased in length, and 
the leaves spread out at right angles to the main axis. As the 
experiment continued there was a noticeable difference in growth 
as compared with the control. The control plants were shorter 
and stockier and deeper green in color. On January 21 antheridia 
and oogonia appeared, ten days after the all-night illumination 
was begun. There was no indication of fruiting in the control. 
The electric illumination was discontinued on March 8. Photo- 
graphs were made on March 26. The development of antheridia 
and oogonia was slow in comparison with that in some of the later 
cultures. Fic. 1, PLATE 11 shows the result of the continuous 
illumination in contrast with the condition of the control culture 
shown in Fic. 4, PLATE 11. When the electric illumination was 
discontinued, the culture with its control was left in the same 
place in the east window. It continued to grow and fruit moder- 
ately throughout the summer, but by September 12 the whole 
culture was dead except for the tips of the plants. A few antheri- 
dia and oogonia were present in the two upper whorls of leaves. 
The tips, 10 cm. long, were transplanted to a new pot of sand 
loam where they subsequently began a rapid vegetative growth. 
By October 19 the plants were approximately 25 cm. in length, 
but no reproductive organs were present on the new growth. 
Since that time, until November 6, a few sporadic antheridia 
and oogonia have been formed on the upper whorls of leaves. 
The control culture began to fruit on June 7. The fruiting 
continued throughout the summer, and on September 12 tips 
