Preliminary Definitions and Illustrations. 15 



is by no means infrequent in the more complex instincts, 

 namely, the serial nature of the adaptation. There is a 

 sequence of activities, and the whole sequence is adaptive 

 in its nature. A further example of the serial nature of 

 instinct of the way in which a number of activities are 

 linked into one elaborately adaptive instinctive chain 

 may be cited.* 



A certain beetle of the genus Sitaris (one of the Meloidce, 

 to which belongs the common oil-beetle) lays its eggs at 

 the entrance of the subterranean galleries excavated by a 

 kind of mason bee (Anthophora). From these eggs the 

 larvae are hatched in autumn as active little insects very 

 different from the ordinary type of beetle grub, having six 

 legs each armed with a sharp curved hook. In the winter 

 they become sluggish, but resume their activity in the 

 spring. And when in April the drones of the bee emerge 

 and pass out through the gallery, the Sitaris larvae fasten 

 upon them. There they remain till the nuptial flight of the 

 bees, when, as the insects mate, they pass from the drone 

 to the female bee. Then again they wait their chance. 

 The moment a bee lays an egg, the Sitaris larva springs 

 upon it, and at length breaks its prolonged fast. " Even 

 while the poor mother is carefully fastening up her cell, 

 her mortal enemy is beginning to devour her offspring ; for 

 the egg of the Anthophora serves not only as a raft, but as 

 a repast. The honey, which is enough for either, would 

 be too little for both ; and the Sitaris, therefore, at its first 

 meal, relieves itself from its only rival. After eight days 

 the egg is consumed, and on the empty shell the Sitaris 

 undergoes its first transformation, and makes its appear- 

 ance in a very different form. ... It changes to a white 



From M. Fabre, as given by Sir John Lubbock in his "Scientific 

 Lectures," 2nd edit. p. 45 (1890). I utilized this example in much the same 

 words in " Animal Life and Intelligence," p. 438. 



