622 



SCIENCE 



[N. S. Vol. XLV. No. 1173 



namely, the supply to the central organs of 

 information, so to speak, as to environmen- 

 tal changes. In these more simplified con- 

 ditions they must be restricted to the simple 

 process of exciting the muscles to activity 

 in consequence of special forms of sensory 

 stimulation. They act, in other words, as 

 a series of local triggers to set off muscular 

 activity in various parts of the body as 

 needed. Here then we see a stage in the 

 evolution of the nervous system in which 

 the sense organ and the muscle are the es- 

 sential parts, but the central organ is to all 

 intents and purposes omitted. Obviously, 

 this stage must precede that in which cen- 

 tral organs are present and these organs, 

 brain, spinal cord and the like, must be 

 looked upon as of later racial origin than 

 sense organs and muscles. It may at first 

 sight seem strange that so significant and 

 all-important an organ as the brain should 

 have been evolved secondarily in relation 

 to sense organs, but such seems to be the 

 case and we are justified, I believe, in stat- 

 ing that animals possess a brain in conse- 

 quence of their having previously had sense 

 organs, not that they possess sense organs 

 because they have a brain. 



The absence of a central organ and the 

 presence merely of sense organs and mus- 

 cles in sea anemones and other like forms 

 makes itself felt in the activities of these 

 animals. As I have already pointed out, 

 that feature above all others that makes one 

 of the higher animals, and especially man, 

 a unit, is the possession of mental traits. 

 Our conscious life affords our strongest 

 claim to individuality. When this is dis- 

 turbed, as in cases of double personality or 

 in the various forms of insanity, even so 

 practical a matter as the law takes cogni- 

 zance and we treat such individuals differ- 

 ently from the common run of men. This 

 unifying infiuence of the nervous system, 

 technically spoken of as its integrative ac- 



tion, is almost completely absent from such 

 animals as the jelly fish and sea anemones. 

 With them individuality is a very subordi- 

 nate character, and it is questionable 

 whether they possess any trace whatever of 

 that trait which we denominate personality 

 in ourselves. They possess no single organ 

 to which the nervous experience of their 

 various parts may be referred to the ad- 

 vantage of the whole. Hence such nervous 

 organization as they have is appropriately 

 styled diffuse, in contrast with the central- 

 ized condition of higher forms. 



The significance of this state of affairs is 

 well seen in the activities of sea anemones. 

 Many years ago it was shown that, if a 

 single tentacle is snipped from the mouth 

 region of a sea anemone and held in sea- 

 water so that the observer can recall which 

 side of the tentacle was originally turned 

 toward the mouth of the animal, the ten- 

 tacle will be found to entangle food and to 

 twist itself in a direction that would be ap- 

 propriate for the delivery of the food to the 

 mouth were that aperture still in its orig- 

 inal relation with the tentacle. This re- 

 sponse, which has been repeatedly con- 

 firmed by others, including myself, shows 

 that each tentacle contains within itself the 

 necessary nerve and muscle to carry out its 

 own movements, and that it is not depend- 

 ent, as in the case of the arms, legs, jaws and 

 so forth of the higher animals, upon a dis- 

 tantly located central nervous organ to 

 initiate, control and subdue its movements. 

 In a similar way I have recently shown 

 that the pedal disc with which many sea 

 anemones creep about wiU, in certain spe- 

 cies, carry out perfectly normal locomotor 

 movements even after the other half of the 

 animal, including the mouth and tentacles, 

 has been cut away. This instance also 

 demonstrates the neuromuscular adequacy 

 of the part of the animal concerned and its 

 relative independence of the rest. Auton- 



