Pulsations in Aortic Arches of the Earthworm. 



27 



large pulsating aortic arches. These arches are sometimes 

 called " primitive hearts." 



These experiments were performed with large strong worms 

 designated as A. B. C. The temperature was raised or lowered 

 as seen by the table with the followiug results: 



1. Change of temperature causes great irritability. 



2. After a short time the worm becomes accustomed to 

 change of temperature, and the aortic arches tend to revert to 

 the original beat. 



See specimen A, temperature 19°; beats 14 16 14. 



A, " 10°; " 8 11 8. 



B, " 10"; '' 8 10 9h. 



3. The pulse beats with greater force at a low tempearture. 



4. Tendency to same rate of beat in same temperature. 



5. The upper limit is reached at 85°, when the pulsations 

 cease. 



Table Showing PulSx\tions in the Aortic Aeches of the 



Eakthwokm, 



