Vol. 51 No. 12 
BULLETIN 
OF THE 
TORREY BOTANICAL CLUB 
DECEMBER, 1924 
A preliminary account of the influence of light and temperature 
on growth and reproduction in Chara fragilis* 
JouNn S. KARLING 
(WITH PLATES II-I3) 
The fruiting in nature of the different species of the Chara- 
ceae is reported by Migula (25), Allen (3), and Robinson (30) 
to occur during the summer and early fall. In undertaking a 
cytological study of nuclear and cell division and fertilization in 
the Characeae three cultures of Chara fragilis Desvaux were 
placed on an east window-sill in the laboratory on September 
24, 1923, to determine whether the stimulus of higher tempera- 
ture and more favorable illumination would lead to the devel- 
opment of reproductive organs at other than normal times. 
The vegetative growth of these cultures was vigorous, but no 
antheridia and oogonia were formed. In view of results recently 
described by Garner and Allard (17), Adams (1), and Harvey 
(19) it was thought worth while to test the cultures as to photo- 
periodism. Consequently on January 8, 1924, as a preliminary 
experiment, two of the cultures were placed under a 60-watt 
120-volt electric light suspended 15 cm. above them and given 
continuous illumination throughout the night. Within a few 
days antheridia and oogonia appeared in abundance on these 
plants, while the control culture remained entirely free from 
reproductive organs. It was then determined to make a further 
preliminary study of the response of Chara fragilis to changes 
in illumination periods and temperature with the particular 
purpose of obtaining material for cytological study. 
* Contributions from the Department of Botany. of Columbia University, 
no. 337. 
[The BuLLETIN for November (51: 443-468) was issued 28 November 1924.] 
469 
