130 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



The dorsal and ventral ganglia are connected by 

 commissures. In addition, they possess a series of 

 peripheral ganglia, the tentacle-ganglia (Tg, Fig. 34), 

 for instance. It is of significance for the segmental 

 theory that the tentacle-ganglia suffice to produce ten- 

 tacle-reflexes, as v. Uexkull has shown in Eledone (2). 

 It has been inferred from experiments on Vertebrates 

 that peripheral ganglia cannot transmit reflexes. 



Now, as regards experiments on the brain of Ceph- 

 alopods, Steiner reports as follows concerning Oc- 

 topus vulgaris : "If the dorsal ganglion on one 

 side be removed, or both commissures of one side be 

 severed, not the slightest change is visible in the life- 

 processes of the animal, for it moves spontaneously as 

 before, attacks its prey (Carcinus mcenas} cleverly, 

 and devours it. But the picture changes if the dorsal 

 ganglion be entirely removed. To be sure the two 

 forms of locomotion are preserved, for the animal 

 creeps with the aid of its arms, or shoots like an arrow 

 through the waves, when water is forced out of the 

 mantle-cavity rhythmically. These movements are, 

 however, no longer spontaneous, for they occur only 

 when the animal is stimulated, neither does it take 

 its food spontaneously. The normal octopus, which 

 is endowed with marked intelligence [?], is wont to 

 observe its surroundings most attentively, but now it 

 sits indifferent to its surroundings, as though idiotic, 

 and only its regular breathing gives evidence that it 

 still lives. Vision is unimpaired, for it draws back 

 when a stick is brought toward its eye." V. Uexkull's 



