BY H, G. CHAPMAN. 



Table ii. 



297 





Dose in mg. 



No. of frogs 



No. of frogs 



No. of frogs 



per gm. 



injected. 



which died. 



which recovered. 



0-05 mg. 



4 







4 



0-06 mg. 



2 







2 



0-07 mg. 



4 







4 



0-08 mg. 



4 



1 



3 



0-09 mg. 



8 



2 



6 



0-10 mg. 



8 



5 



3 



0-11 mg. 



7 



5 



2 



0-12 mg. 



7 



5 



2 



0-13 mg. 



5 



4 



1 



0-14 mg. 



6 



4 



2 



0-15 mg. 



4 



2 



2 



0*16 mg. 



4 



3 



1 



0'17 mg. 



3 



3 







0'18mg. 



4 



3 



1 



0*19 mg. 



2 



1 



1 



0-20 mg. 



4 



4 



i 



0-21 mg. 



2 



1 



1 



0-23 mg. 



1 



1 







0-25 mg. 



1 



1 







0-27 mg, 



1 



1 







Sixty-six experiments were performed with summer frogs. 

 Thirty-seven frogs received doses of more than 0*1 mg. per gm. 

 body-weight. Of these four survived. Thirty-six experiments 

 were performed with winter frogs. Eighteen received doses of 

 more than 0*1 mg. per gm. body weight. Of these eight recovered. 

 It would thus appear that winter frogs were more resistant than 

 summer frogs. A number of observations were made on frogs 

 wbich had been more than two months in the laboratory tank. 

 It appeared that the resistance to strychnine was slightly dimin- 

 ished, but the number of experiments was too small to obtain 

 sufficient numerical data to calculate a minimal lethal dose. 

 Experiments 22 to 27 in Table i., represent part of the series with 

 frogs from the laboratory tank, and experiments 24 to 42 repre- 

 sent part of the series with frogs caught in the Botany swamp a 

 few days previous to injection. 



The behaviour of Hyla aurea after the introduction of strych- 

 nine was characteristic when the dose reached a certain value. 



