2 Professsor J. Arthur Thomson on 



biological problem may be found in the case of the partnership 

 between hermit-crab and sea-anemone. The hermit-crab, having 

 a fairly well-developed brain may be appreciatively aware of what 

 he does when he puts a partner, sea-anemone, on his back, but 

 what are we to say of the more than acquiescent partner which 

 has no nerve-ganglia at all 1 



At the lowest level Ave have the behaviour of the Bryony 

 binding itself to the hedgerow, the Venus Fly-Trap shutting on 

 the insect, the starfish surrendering an arm and thus saving its 

 life, or the sea-anemone creeping up the hermit-crab's leg. There 

 are inborn structural and functional adaptations which work 

 effectively when the trigger is pulled. In the absence of any 

 nerve-ganglia, we dare not use any big psychological word like 

 perception or inferring. 



At the highest level we have Rooks breaking freshwater 

 mussels by letting them fall from a height, or the Thrush breaking 

 the snail's shell on a stone, or the skua chivying other gulls and 

 forcing them to disgorge, where it is perhaps warrantable to speak 

 of deliberate intelligence, of experimental inference. But it is 

 difficult to decide how many apparently bright ideas, like the 

 7nole's cache of decapitated earthworms, are as clever as they at 

 first sight seem. It is difficult to know how far down in the scale 

 we can get presumptive evidence of intelligent invention. To 

 what extent did real inventiveness enter into the sea-swift's 

 making of a nest out of its salivary juice, or into the neat device 

 })y which the snake, Dasypeltis, breaks the birds' eggs which it 

 swallows, or into the extraordinary fashion in Avhich Darwin's 

 frog rears its young ones in its croaking sacs, or into the way in 

 which the male of the New Guinea Fish, Kurtus, carries his 

 family on the top of his head. The testing and trying of new 

 peculiarities of structure and of function — new departures arising 

 as germinal variations, might lead to the racial establishment 

 of inventive devices which were intelligently appreciated and 

 approved of by the animal, though they were not intelligently 

 thought out or devised. 



