242 



VASIL OBRESHKOVE 



5. Method 



If tadpoles subjected to various intensities of light are respon- 

 sive with any degree of regularity, they ought to furnish measure- 

 ments of the photic reactions for an examination of the Bunsen- 



{qWuWWji 



'NX 



1M> 



js 



Fig. 1 Diagram of apparatus used for testing the sensitivity of tadpoles of 

 Rana clamitans to various intensities of light. a,b, small rectangular table; 

 c, bicycle tire; n, rectangular board; v, porcelain dish; q, dim light inclosed in a 

 box; m, mat; s, source of light. 



Roscoe law, especially if any relation between the degree of 

 stimulation and the time which elapses before a response is 

 noted can be ascertained. The intensities generally used were 

 0.3, 0.71, 1.2, 5, 10, 15, 20 and 30 candle-meters. To these, 

 in the latter part of the work, were added 60, 200, and 500 candle- 



