632 LIFE : OUTLINES OF GENERAL BIOLOGY 



the oix^ration of some degree of mental awareness which prompts 

 the animal to put its inborn gifts to the test, especially when there 

 is any novelty in the circumstances. Instead of looking for "mind" 

 in the orii^in of the reflex, it may be shrewder to look for it in the 

 testing of the hereditary equipment. If one may say so, the organism 

 plays its hereditary cards. This point of view is justified, we think, 

 by the familiar easels where animals in the course of their lifetime, 

 and sometimes in the course of brief exj^Timcnts, are able to 

 improve upon their hereditary equipment by establishing novel 

 reflexes on the basis of profitable associations. 



Some of the simplest reflexes are very instructive in this con 

 nection. In sc^a-anemones there is no central nervous system, 

 nothing more than a network of nerve-cells. Sensory neurons on a 

 tentacle are stimulated by the touch of a fragment of flesh; the 

 nerve impulse passes to a deeper motor neuron and thence to the 

 muscle, the result being that the tentacle curves round the food 

 and bends in towards the mouth. In many cases it passes on the 

 booty to another tentacle, which continues the transport. This is a 

 very simple reflex action, and it suffices for a considerable part of 

 the sea-anemone's everyday life. But deeper scrutiny shows that the 

 behaviour of sea-anemones is not so simple as it appears at first 

 sight. Unpalatable fragments are often refused; sometimes they are 

 positively rejected. In some cases when the sea-anemone is fed with 

 crab's flesh and filter-paper in rapid succession, it soon comes to 

 reject the unprofitable. In two to five days a particular tentacle, as 

 Fleure and Walton showed, will refuse to grip the filter-paper. Yet 

 inexperienced adjacent tentacles fell into the trap, though only 

 once or twice. The profiting by experience was somehow transferred 

 by the network of nerve-cells to neighbouring tentacles. Perhaps 

 there is here a glimmering of awareness, feeble because the nervous 

 system is so diffuse. Prof. G. H. Parker cheated the tentacles of 

 one side of an anemone till they would not be cheated anymore, but 

 he found that those on the other side were quite liable to be deceived 

 by faked food. Our view is that most sea-anemones get along very 

 well without "mind", in virtue of their inborn and acquired neuro- 

 muscular linkages; and yet sometimes there is in the background a 

 hint of an inner awarene.ss that enables the animal to use its reflexes 

 in a somewhat new and more unified way. Thus the beautiful 

 Anthea allows a spider-crab to shelter between its ba.se and the 

 rock, and stretches down one of its long tentacles to grip the booty 

 that the crustacean has lugged home to its retreat. It is too soon to 

 offer an argument; but it appc^ars to us very difficult to account for 

 the details of the much-studied commensali.sm or mutually beneficial 

 partnership between sea-anemones and hermit-crabs without 

 crediting both parties with the stirrings of mind. 



Not far from the level of automatised reflex actions, but with 



