550 Causes and Course of Organic Evolution 



structures for bringing the organism into most direct, rapid, 

 and varied contact with its environment. The arms therefore 

 of Loligo or Octopus are now tactile, prehensile, fighting, loco- 

 motory to a slight degree, and food selective. In corresponding 

 degree then to perfectioning of the arms, the originally diffuse 

 ganglia of molluscs have become condensed in Nautilus to a 

 broad ring round the gullet, as well as distinct buccal, phar- 

 yngeal, and visceral masses. In Loligo even these ganglia have 

 become condensed into a huge ganglionic swelling that is 

 almost on a level with the insertion of the arms, the eyes, the 

 probable olfactory, the auditoiy, and the geotropic organs. 

 Here is strongly suggested a direct action and reaction relation 

 between the environal organs — especially the arms with varied 

 functions — and the "greatly enlarged "brain" of the compara- 

 tively recent genus Loligo. 



One result here, and biologically a very striking one, has 

 been that the external protective shell has gradually been dis- 

 carded, and the now soft-bodied animal trusts to less cumbrous 

 but more intelligent means for offense and defense. This 

 method has largely been adopted and has largely proved suc- 

 cessful amongst many groups of animals in the struggle for 

 existence. The shelled and mailed ones have often disappeared 

 • — like the cumbrously cuirassed knights of old — while the soft- 

 bodied but resourceful ones have usually "pulled through." 



That Loligo and related higher cephalopods have an extreme 

 agility, resourcefulness, and caution is already fully recognized 

 by naturalists, though abundant observations and experiments 

 are still much needed. But the fact that the extensive and 

 striking pigment-cell system is directly connected with the optic 

 nerve (133: 380), and that the color of the animal can be 

 changed almost instantly from gray to steel, to bluish, to pur- 

 plish, to crimson-brown, and back again to gray, indicates 

 capacity for rapid and delicate response to nerve stimuli. 

 Again Romanes {50: 29), quoting first from Schneider, says: 

 "The Cephalopoda show unmistakable evidence of conscious- 

 ness and intelligence. This observer had an opportunity of 

 watching them for a long time, in the zoological station at 



