3i6 



UGHT ANV THE BEHAVIOR OF ORGANISMS 



noch vollig aufrecht. Eine Stunde spater hatten die vom 

 Indigo bis ins Ultraviolett reichenden Keimlinge sich 

 stark hankenformig gegen die Lichtquelle hinge wendet, 

 gleichzeitig neigte sich das im Orange stehende Pflanzchen 

 schwach vor. Der im Gelb befindUche Keimling bheb 

 aber bis ans Ende des Versuches vollkommen aufrecht." 

 The roots of Sinapis alba (white mustard) were found to 

 respond in the spectrum in all essentials like the stems of 

 Vicia sativa, except that they turned from the light in place 

 of toward it. 



Fig. 35. Graphic representation of the reaction of several plants in light diflfer- 

 ing in wave-length. A-H represent Fraunhofer lines in the spectrum. The 

 curves i, 2, and 3 were constructed by tabulating as ordinates the reciprocals of 

 the time required to induce a response under the different light conditions: i, stem 

 of Vicia seedling; 2, stem of cress seedling; 3, etiolated willow shoot. After Wiesner 

 (1879, p. 191). 



The results of numerous observations on the reactions 

 of different seedlings behind different absorbing media all 

 of which were spectroscopically tested are graphically rep- 

 resented in Fig. 35. It is interesting to note that these 

 results agree fairly well with those obtained in the spec- 

 trum, although the different colors were in no instance 

 monochromatic. Wiesner claims that yellow is not merely 



