Physiology of Ventral Nerve Cord of Myriapoda. 277 



on distal stimulation includes this delay while the records obtained 

 on proximal stimulation do not, it is obvious that the rate of prop- 

 agation of the impulse as calculated from the latent periods of 

 these records would be less than the actual. For that reason it 

 would be desirable to check up the measurements on these com- 

 paratively short centipedes by experiments on larger representa- 

 titves from the tropics, as in larger specimens this possible source 

 of error can be practically excluded. 



To give an idea of the variability of the latent time in the 

 records obtained by this method, three series of experiments are 

 given in detail in Tables I, IV, and V. All of the experiments are 

 summarized in Tables II, III, V and VII. The character of the 

 tracings has already been referred to. It is amply illustrated in 



figs. 2 to 6. 



TABLE I. 



Scolopendra morsitans. Antero-posterior. Detail of experi- 

 ment No. 2, Table II, October 17, 1902. Temperature, 16° C. 



TOTAL LATENT TIME IN SECONDS. 



Distal. Proximal. 



0.045 0.028 



0.047 ^-^^5 



0.048 0.027 



0.047 0.026 



0.045 0.025 



0.047 °-°^5 



Average. . . 0.046 0.026 



Transmission time 0-02 sec. 



Length of nerve-cord 5 ^"^• 



Rate 2.50 m. per sec. 



TABLE IL 

 Summary of the measurements of the antero-posterior rate in 

 the nerve-cord of Scolopendra (No. 1-8) and Scolopocryptops 

 (No. 9-13). The length of nerve-cord involves from 13 to 17 

 segments. 



