The Story of Evolution 79 



some pollen from the stamens, kneads it into a pill-like ball, and 

 stows this away under her chin. She flies to an older Yucca flower 

 and lays her eggs in some of the ovules within the seed-box, but 

 before she does so she has to deposit on the stigma the ball of 

 pollen. From this the pollen-tubes grow down and the pollen- 

 nucleus of a tube fertilises the egg-cell in an ovule, so that the 

 possible seeds become real seeds, for it is only a fraction of them 

 that the Yucca Moth has destroyed by using them as cradles for 

 her eggs. Now it is plain that the Yucca Moth has no individual 

 experience of Yucca flowers, yet she secures the continuance of 

 her race by a concatenation of actions which form part of her 

 instinctive repertory. 



From a physiological point of view instinctive behaviour is 

 like a chain of compound reflex actions, but in some cases, at least, 

 there is reason to believe that the behaviour is suffused with aware- 

 ness and backed by endeavour. This is suggested in exceptional 

 cases where the stereotyped routine is departed from to meet 

 exceptional conditions. It should also be noted that just as ants, 

 hive bees, and wasps exhibit in most cases purely instinctive be- 

 haviour, but move on occasion on the main line of trial and error 

 or of experimental initiative, so among birds and mammals the 

 intelligent behaviour is sometimes replaced by instinctive routine. 

 Perhaps there is no instinctive behaviour without a spice of 

 intelligence, and no intelligent behaviour without an instinctive 

 element. The old view that instinctive behaviour was originally 

 intelligent, and that instinct is "lapsed intelligence," is a tempting 

 one, and is suggested by the way in which habitual intelligent ac- 

 tions cease in the individual to require intelligent control, but it 

 rests on the unproved hypothesis that the acquisitions of the indi- 

 vidual can be entailed on the race. It is almost certain that 

 instinct is on a line of evolution quite different from intelligence, 

 and that it is nearer to the inborn inspirations of the calculating 

 boy or the musical genius than to the plodding methods of intel- 

 ligent learning. 



