xc Journal of Comparative Neurology. 



ment of the central nervous system, but in Balanoglossus the central 

 system is solely represented by the apical plate of the preoral lobe. 

 This plate disappears during the development and is substituted for 

 by the medullary tube. , In the ascidian and Amphioxus the apical 

 nervous system does not develop in any stage. Thus the vertebrate 

 lacks the preoral nervous system because of its transformation in lower 

 types into an organ of fixation or locomotion. 



The Cortical Physiology of Mastication and Deglutition. 1 



In the dog and the rabbit the common centre of mastication and 

 deglutition lies on the cephalo-lateral border of the centre for the ex- 

 tremities. Electrical stimulation of this region pro- 

 duces not merely contraction of the masseter and its 

 associated muscles, but the coordinated movements 

 of the lips and tongue. If the animal is not too 

 deeply narcotized a complete act of swallowing fol- 

 lows from the same stimulus. 



The accompanying diagram illustrates one set 

 from a number of typical curves as recorded on a 

 kymograph : No. i indicates the duration of the Fig3- cortical centre 

 stimulus, No. 2 marks seconds, No. 3, the move- of mastication and 



e , , • vr a r deglutition in the 



ments of the lower jaw, No. 4, the movements of ra ^ bit 

 the larynx. 



1 



3 -nTnNniW" IW^^f^m 



j-mr 



/^ 



Fig. 4. 



Further localization experiments on the cut surface of the brain 

 after the removal of successive transections from before backwards re- 

 veal the course of the subcortical tracts. They pass ventrad through 



1 Rethi, L. Das Rindenfeld, die subcorticalen Bahnen und das Coordina- 

 tionscentrum des Kauens und Schluckens. Sitzber. kais. Akad. der Wiss. Wien. 

 CII, 3-7, 1893- 



