BIOPSYCHOLOGICAL 627 



first. Pompilus has three devices, and this possibiHty of alternatives 

 leads us to look out for intelligence. Its first device is to break off 

 the doors — a proceeding that brings the spider up to try to repair the 

 damage. The spider is then caught. A second device is to insert its 

 tail in the first entrance and then withdraw it, keeping an eye 

 meanwhile on the second door by which the spider is likely to try 

 to escape. The wasp's third device is to rap first at one door and 

 then at the other, until the spider becomes excited and makes a 

 rush. But the wasp is almost invariably too quick for the spider. 

 The ingenuity and variability of its behaviour must be regarded 

 as indicative of inteUigence. There seems to be a plastic appreciation 

 of the situation. 



While the instinctive is an expression of non-intelligent racial 

 enregistration, and does not necessarily require any "learning" or 

 imderstanding, one must not think of instinct and intelligence as 

 quite separate entities or faculties. The whole hfe is a unity, and 

 one must think of instinctive behaviour as possible without much 

 mental correlate, whereas "mind" is the true inwardness of all be- 

 haviour that is worthy of being called intelligent. What is inherited 

 in the predominantly instinctive animals is a set of neuro-muscular 

 predispositions of a very precise type, yet accompanied, no doubt, 

 by a stream of feeling, as well as by a certain degree of awareness 

 and the bent bow of endeavour. What is inherited in the predomi- 

 nantly intelligent animals is a highly developed brain, and the 

 correlated mental aspect of imaging, experimentation, memory, and 

 enjoyment. 



(VI) RHYTHMS. — It seems useful to group by themselves what 

 may be called enregistered rhythms, where there is a periodic 

 expression of a particular kind of activity. The well-known Planarian 

 worm called Convoluta ascends to the surface of the sand when the 

 tide goes out and disappears below the surface whenever the tide 

 comes in. This is more than reaction to stimuli, for the little worms 

 manifest the same periodicity when transferred to a tideless aqua- 

 rium, and continue doing so for a week or more. But we dare not 

 use any psychological word like memory; what happens is due to a 

 racial bodily enregistration. There is a hereditary rhythmic reactivity 

 to periodic changes in the gravitational conditions, but the awaken- 

 ing of the reaction is probably helped by the changes in the amount 

 of water and light. In a dark aquarium the rhythm disappears 

 quickly. It is probable that racially estabHshed rhythms correlated 

 with external periodicities play a part in animal behaviour greater 

 than has been yet recognised, especially in regard to seasonal 

 activities. It is probable that something of the same rhythmicity of 

 impulse is expressed in the restlessness of migrant birds when the 

 time comes for their journey, and at this relatively high level there 



