500 The Botanical Gazette. [November, 
vertically upright to a directly inverted, and it was found that 
the law of the ‘‘angle of incidence” of light does not hold 
when the light is given from below the horizontal. Further 
‘that when an orthotropic organ is acted upon by two oppos- 
ing stimuli, the resultant curvature will depend not only on 
the relative force of the stimuli but also on the position of the 
organ.” The results of Dr. Czapek’s work form an important 
addition to those which oppose the theory of ‘‘specific energy” 
of Johannes Miiller which is upheld by Sachs and which forms 
the basis of Noll’s speculations in his Heterogene Induktion. 
Incidentally, the prevalent views concerning plagiotropic or- 
gans are placed open to question.—D. T. MAc DOUGAL. 
