1914] JOLIV ETTE—PILOBOLUS 121 
The question as to what properties of the protoplasm cause it 
to be more sensitive to rays of one wave-length than to those of 
another remains unsolved, and, like that as to why it responds to 
one of two stimuli to the complete exclusion of the other, it must 
await a better knowledge of the organization of the plasma. 
LELAND STANFORD JUNIOR UNIVERSITY 
CALIFORNIA 
LITERATURE CITED 
1. ALLEN, R. F., and Jotivetre, H., Some light reactions of Pilobolus. Trans. 
Wis. Acad. Sci. 1912. 
. GUTTENBERG, RitrEeR von, Uber das Zusammeénwirken von Geotropismus 
und Heliotropismus in parallelotropen Pflanzentheilen. Jahrb. Wiss. Bot. 
45:193-231. 1907. . 
3. , Uber das Zusammenwirken von Geotropismus und Heliotropismus 
und die tropistische prea in reiner und unreiner Luft. Jahr 
Wiss. Bot. 47:462~492. 
- NOLL, F. eee fst Leipzig. 1892. 
. Ricuter, O., Uber das Zusammenwirken von Heliotropismus und Geo- 
“Fopismus. nee we Bot. 46:481-—502. 1909. 
N 
on 
