author's abstract of this paper issued 

 by the bibliographic service, august 5 



THE PHOTIC REACTIONS OF TADPOLES IN RELATION 

 TO THE BUNSEN-ROSCOE LAW 



VASIL OBRESHKOVE 



Zoological Laboratory, Harvard University. 



NINE FIGURES 



CONTENTS 



I. Introduction 235 



II. Historical review 237 



III. Material and methods 238 



1. Selection of animals for experimentation 239 



2. Apparatus 241 



3. Method 242 



IV. Dynamics of sensitivity to light 244 



V. Photosensitivity of the skin as compared with the eye 252 



1. The skin 252 



2. The eye 259 



VI. Velocity of changes in the receptors with higher light intensities and 



the duration of secondary processes following sensitization 261 



VII. Photosensory recovery 268 



VIII. The process of fatigue 270 



IX. Discussion 273 



1. The nature of the process 273 



2. The photoreceptors 275 



X. Conclusions 277 



XI . Bibliography 278 



I. INTRODUCTION 



The principle of transference of energy implies that for a 

 given amount of energy used in the incitement of a reaction 

 there must be evoked an equivalent effect. This principle has 

 led to the development of a number of laws in general chemistry, 

 which furnish expressions of the relation of the amount of energy 

 received, to the effect produced, and the progression of this 

 effect with the time of action and active masses. 



In 1862 Bunsen and Roscoe showed that in order to produce 

 equal shades of darkness on silver-chloride papers exposed to 



235 



