ii.l THE NATURE OF INSTINCT 171 



tive of individuals, although individuals collaborate in it. 

 Compare the different forms of the same instinct in 

 different species of hymenoptera. The impression de- 

 rived is not always that of an increasing complexity made 

 of elements that have been added together one after the 

 other. Nor does it suggest the idea of steps up a ladder. 

 Rather do we think, in many cases at least, of the circum- 

 ference of a circle, from different points of which these 

 different varieties have started, all facing the same centre, 

 all making an effort in that direction, but each approach- 

 ing it only to the extent of its means, and to the extent 

 also to which this central point has been illumined for it. 

 In other words, instinct is everywhere complete, but it is 

 more or less simplified, and, above all, simplified differently. 

 On the other hand, in cases where we do get the impression 

 of an ascending scale, as if one and the same instinct had 

 gone on complicating itself more and more in one direction 

 and along a straight line, the species which are thus ar- 

 ranged by their instincts into a linear series are by no means 

 always akin. Thus, the comparative study, in recent 

 years, of the social instinct in the different apidae proves 

 that the instinct of the meliponines is intermediary in 

 complexity between the still rudimentary tendency of the 

 humble bees and the consummate science of the true bees; 

 yet there can be no kinship between the bees and the 

 meliponines. 1 Most likely, the degree of complexity of 

 these different societies has nothing to do with any greater 

 or smaller number of added elements. We seem rather to 

 be before a musical theme, which had first been transposed, 

 the theme as a whole, into a certain number of tones, 

 and on which, still the whole theme, different variations 

 had been played, some very simple, others very skilful. 



1 Buttel-Reepen, "Die phylogenetische Entstehung des Bienen- 

 staates" (Biol. Centralblatt, xxiii. 1903), p. 108 in particular. 



