478 KARLING: GROWTH AND REPRODUCTION IN CHARA 
SERIES B 
GCoteered, Tita park ood a a eee i eee ee. March 26 
Grown. on- shelf in? south window. .... 03. ces. cous March 26—April 8 
Grown on shelf in south window under daily electric illumination from 
BUHSEL COT Dy Tso eae Oh betes ew agen es April 8-May 11 
Grown on shelf in south window with only daylight illumination 
ay 11-Nov. 6 
Culture B consisted of two jars containing approximately 
two hundred shoots which had been brought indoors on March 
26 and kept in a south window where the direct sunlight fell 
on the jars from 9 a. m. until 4 p.m. The control cultures were 
placed beside the two jars. The intensity of illumination in the 
early morning and late afternoon when the sun was not shining 
on the cultures, was measured with a photometer and found to 
be approximately 50 foot-candles. The electric light supplied 
was the same as in the preceding cultures, with the exception 
that it was turned off at 10 p. m. Antheridia and oogonia ap- 
peared four days after the artificial illumination was started. 
Photographs were made 33 days after the first reproductive 
organs appeared. Fic. 3, PLATE 12 shows the extent of fruiting 
at that time. The length of day, in the meantime, had increased 
one hour and ten minutes. 
The production of antheridia and oogonia in this culture was 
not as abundant as in the preceding one. About half of the 
plants had formed no reproductive organs when the photo- 
graphs were made. The vegetative growth, however, was strik- 
ing. In nature, according to Migula, Chara fragilis does not 
reach much more than 75 cm.inlength. Inone jar of this culture, 
however, the plants attained a length of over a meter. The 
internodes were approximately 10 cm. long, but less than normal 
in diameter. All plants in the culture grew well during the 
summer. There was no apparent etiolation such as was so 
characteristic of the preceding culture. Fruiting throughout 
the summer was moderate. On September I2, tips of the 
plants about 10 cm. long were cut off and transplanted. By 
October 19 these transplanted tips had grown to a length of 30 
cm., and of the hundred or more plants in the culture three 
showed a few antheridia and oogonia. On November 6, the 
plants were growing vigorously with occasional reproductive 
organs in eight of the plants. The stock culture from which 
