ANIMAL BEHAVIOR — WELLS 419 



patterns appear over and over again on the tracings; (c) by special 

 means (such as watching worms in glass tubes) you find out what 

 particular activities these patterns accompany. This is the most 

 laborious stage, and it must be confessed that one's knowledge of the 

 script of any species is never complete. But even with partial under- 

 standing the method is useful. One can set up the apparatus, leave it 

 to run for a very long period of time, and afterward read from the 

 tracings what has happened and when. It is worth emphasizing that 

 one's interference with the worms is minimal ; they are perfectly free 

 to move about in their tubes or burrows, and one only imposes an 

 imperceptibly small resistance on their water currents. One finds out, 

 in this way, how they behave when they are left alone. 



One of the results of this method is to show that the lugworm is a 

 creature of moods. It has several alternative patterns, any one of 

 which it can write on the paper. It may behave as I have already de- 

 scribed, feeding in little bursts and discharging a sand cylinder every 

 40 minutes ; these acts affect the water movements, and gives the record 

 a very characteristic appearance. Alternatively, it may lie still and do 

 nothing; or it may trace violent chaotic wiggles that I cannot pretend 

 to understand ; or it may trace other rhythmic patterns, without feed- 

 ing, that there is no time now to describe. A long-term record of its 

 behavior always shows these "moods," each of them generally persist- 

 ing for several hours and then passing suddenly into another. The 

 patterns can of course be modified by external circumstances ; but what 

 I have just said is true of worms living, as far as one can judge, in very 

 uniform and favorable conditions. It looks as if the lugworm's be- 

 havior is mainly governed by an elaborate inherent organization, per- 

 haps even up to the level of the long-term changes of mood. 



The same kind of thing can be seen in other marine worms. Their 

 activities are patterned in time, sometimes with strikingly regular 

 rhythms ; and in some cases there are alternative rhythms and changes 

 of mood. A point that comes out very clearly when the tracings of 

 different kinds of worms are compared, is that the more regular pat- 

 terns are characteristic of the species. There is, for example, a family 

 of worms — the Sabellidae — that live in tubes of their own construc- 

 tion, spreading their crowns of feathered tentacles in the sea water, 

 and eating the minute suspended particles which these tentacles en- 

 trap. Water-current records of two species of this family have al- 

 ready been published, and I have unpublished material on two more. 

 All of them have complicated activity-time patterns, and — although 

 they all live in very much the same way — the patterns are in part 

 specific. Each species has its own characteristic kind of wiggle, which 



