RATE OF THE HEART-BEAT IN A CRUSTACEAN. 245 



At 33 the whole animal went into convulsive tremors, and at 

 35 the heart stopped permanently. 



Rate at 2 1 Rate at 2 5 



Rate~atTi i = 5 ' Rate at 15 = 



Rate at 29 Rate at 31 



Rate at 19 ? ' Rate at 2! 



EXPERIMENT 6. 



Temperature. Beats per Second. Remarks. 



11 2. 1 1 Beat irregular 



13 2.53 



15 2.53 " regular 



19 2.67 " " 



21 4.05 



23 4.80 " 



25 5.56 



29 6.50 " " 



29 5-33 After a fall and subsequent 



rise in temperature. 



Rate at 21 Rate at 23 Rate at 25 



Rate at 1 1 = l ' g2 ' Rate at 13 = I-9 ' Rate at 15" = 



Rate at 29 Rate at 29 



- = 2.3o; =r- - (second observation) = 2. oo. 



Rate at 19 Rate at 19 



EXPERIMENT 7. 



Temperature. Beats per Second. 

 11 1.64 



15 2. 3 8 



17 2.63 



19 2.98 



*2I 4.53 



21 4-55 



21 4.48 



2 5 5-33 



27 5-4 



29 5-15 



Average rate at 2 1 Rate at 2 5 



"RateiTiT 5 ' Rate at 15 



Rate at 27 Rate at 29 



RatTatTp" 2 ' 5 ' Rate at 19 



The beat was regular throughout the observations in this ex- 

 periment. The observations were made in the following order, 



