CONTIRBUTIONS TO THE PHYSIOLOGY OF THE 



VENTRAL NERVE-CORD OF MYRIAPODA 



(CENTIPEDES AND MILLIPEDES). 



(Six Figures.) 



A. J. CARLSON. 



(From the physiological laboratory of Leland Stanford, Jr., University.) 



I. The Rate of Propagation of the Nervous Impulse in the 

 Ventral Nerve-Cord. 



The measurements of the rate of propagation of the nervous 

 Impulse were made in the fall of 1902. Their publication has 

 been delayed with the v- iew of obtaining large centipedes from the 

 tropics for the work, so as to exclude a possible source of error in 

 the measurements when smaller specimens are made use of. The 

 attempts to obtain larger centipedes than those available here in 

 California have not proved successful, and the further work must 

 therefore be postponed till more favorable material becomes avail- 

 able. 



The structure and relations of the central nervous system of 

 the centipedes and millipedes are essentially the same as in the 

 annelid worms. Each segment Is provided with a pair of ganglia, 

 which are connected by transverse commissures and by longitudi- 

 nal commissures with the neighboring anterior and posterior pairs 

 of ganglia. This nerve-cord is situated ventral to the gut. In 

 the anterior or head segment It Is connected by a commissure on 

 either side of the oesophagus with the supra-cesophageal ganglion 

 or "brain." 



