IKKARLING: GROWTH AND REPRODUCTION IN CHARA 475 
Io cm. long were transplanted to a pot of fresh sand and loam. 
A good vegetative growth followed, and on October 13 a few 
antheridia and oogonia were observed on this new growth. By 
November 6, however, these had fallen off. 
The plants of Series 0, Culture 0-2, consisting of a single 
jar, were brought in from the park on December 28, 1923 and 
grown in the east window alongside Culture 0-1. Its growth, 
however, had not been as vigorous when on January 18 it was 
placed inside of the window under the same light and temperature 
conditions as 0-1. Antheridia and oogonia were formed twenty- 
one days later, on February 9. No reproductive organs were 
present in the control culture at that time. Culture 0-2 con- 
tinued to fruit during the summer, but the plants were very 
slender with long internodes and short leaves. On September 
12 anumber of 10 cm.-long tips of these plants were transplanted. 
Growth was very slow, and by the first of November the entire 
culture was dead. The original culture, pruned down on Sep- 
tember 12, began to grow rapidly, and on October 19 the new 
growth was approximately 8.5 cm. long. Antheridia and 
oogonia were abundant on the new growth. By November 6, 
the longest plants were about 25 cm. long, with a few reproductive 
organs in the apical whorl of leaves. 
Series 0, Culture 0-3, consisting of two jars, contained about 
seventy-five plants of Chara fragilis which were collected in 1922 
and had been growing in the greenhouse for two years without 
forming reproductive organs. This culture had been subject to 
usual greenhouse conditions in a house used for ordinary herba- 
ceous annuals. On January 22, 1924, the jars were placed under 
a 75-watt 120-volt light suspended 1 meter above. The light 
was kept burning throughout the entire night. On March 14, 
fifty days later, antheridia and oogonia appeared in the two 
uppermost leaf whorls of the plants. The night temperatures in 
the greenhouse were considerably lower than in the laboratory 
in which Cultures 0-1 and o-2 were grown. Fic. 2, PLATE II 
shows this culture in contrast with its control. Nearly every 
oogonium formed in this culture developed mature oospores, 
while from the thousands of antheridia and oogonia formed in 
0-I and 0-2, less than twenty-five mature oospores were devel- 
oped. In these latter cultures the oogonia turned white in 
color and dropped off after attaining full size. 
