482 KARLING: GROWTH AND REPRODUCTION IN CHARA 
of reproductive organs; whereas in the other cultures the anther-. 
idia and oogonia were developed only at the four uppermost 
nodes. None of the oogonia, however, developed mature 
oospores. The appearance of the antheridia and oogonia was 
normal in every respect. Motile antherozoids were produced 
in abundance, and the eggs were completely filled with large 
starch grains, 
The vegetative growth was quite striking in appearance. 
At the time the culture was placed in the dark room the plants 
were only 15 cm. in length, but when the photographs were made 
on May 7 they had increased about 10cm. FIG. 3, PLATE 12 
shows the character of the vegetative growth and the extent of 
fruiting. When compared with the plants of the other cultures 
it'is evident that the leaves are longer and the internodes shorter. 
It does not follow, however, that this is solely due to light and 
temperature differences. The plants of Culture E reached the 
surface of the water, bent over and continued to grow. It has 
been observed in other instances that when this occurs the 
internodes are shorter and the leaves. longer than in normal 
cultures. Such behavior is frequently observed in Chara growing 
in shallow ponds and lakes. 
The temperature of the water was fairly constant throughout 
the period of this experiment. The range of temperature 
extended between 23° and 27° C., and the fluctuation, as shown 
in CHART I, was not over three degrees. This culture throws 
interesting light on the relation of intensity of illumination to 
the formation of antheridia and oogonia. The intensity of a 
60-watt 120-volt lamp is less than ten foot-candles, while 
that of the direct sunlight at midday might be as high as 
12,000. Yet the plants in Culture E produced antheridia and 
oogonia in greater abundance and in shorter time than plants 
which had been grown in the direct rays of sunlight for several 
hours each day. These results are in harmony with those of 
Garner and Allard, who found that the soy bean grown under 
one-fourth and one-third natural light intensity matured and 
produced seed in the same length of time as plants which had 
been grown in full sunlight. Klebs secured somewhat similar 
results with Vaucheria when the cultures were shaded. Using 
artificial light, he found zoospore and gamete production to be 
more dantin anill tion equivalent to forty foot-candles 
than in higher intensities. 
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