CHAPTER VIII 



EXPERIMENTS ON MOLLUSKS 



The literature on the functions of the central 

 nervous system of Mollusks is extremely meagre. 

 It is nevertheless valuable, as it furnishes us with 

 further proofs of the theory that the simple and 

 rhythmical spontaneity, as well as reflex processes, do 

 not depend upon the brain or specific peculiarities of 

 the ganglia. A Gastropod whose brain (g, Fig. 33) 



has been removed 

 continues to move 

 spontaneously. Stei- 

 ner has observed 

 this in a transparent 

 pelagic species of 

 snail, Pterotrachea, 



FIG. 33. SCHEMATIC REPRESENTATION OF that IS about TO cm. 

 THE CENTRAL NERVOUS SYSTEM OF A 

 SNAIL (PALUDINA VIVIPARA). 



g, brain ; P, pedal ganglion. (Modified after Leydig.) 



transformed into a 



swimming organ. Neither one- nor two-sided de- 

 struction of the supracesophageal ganglion has the 

 slightest influence upon the character and the 



128 



p 



s (0- The foot 

 of this snail has been 



