4 Evolution and Adaptation 



is the means of securing the insects used for food, it fulfils 

 a purpose necessary for the welfare of the spider. 



The making of the nests by birds appears to be also in 

 large part an instinctive act ; although some writers are 

 inclined to think that memory of the nest in which the 

 young birds lived plays a part in their actions, and imitation 

 of the old birds at the time of nest-building may, perhaps, 

 also enter into the result. It has been stated that the first 

 nest built by young birds is less perfect than that built by 

 older birds, but this may be due to the bird's learning some- 

 thing themselves in building their nests, i.e. to the perfecting 

 of the instinct in the individual that makes use of it. In any 

 case much remains that must be purely instinctive. The 

 construction of the comb by bees appears to be largely, per- 

 haps entirely, an instinctive act. That this is the case was 

 shown by isolating young workers as soon as they emerged 

 from the cell, and before they could have had any experience 

 in seeing comb built. When given some wax they set to 

 work to make a comb, and made the characteristic six-sided 

 structures like those made by the bees in a hive. The forma- 

 tion of so remarkable a structure as the comb is worthy of 

 admiration, for, with the greatest economy of material, a 

 most perfect storeroom for the preservation of the honey is 

 secured. This adaptation appears almost in the nature of 

 foresight, for the store of honey is used not only to feed the 

 young, but may be drawn on by the bees themselves in time 

 of need. It is true that a comparison with other kinds of 

 bees makes it probable that the comb was first made for the 

 eggs and larvae, and only later became used as a storehouse, 

 but so far as its form is concerned there is the same economy 

 of constructive materials in either case. 



The behavior of young birds, more especially those that 

 take care of themselves from the moment they leave the egg, 

 furnishes a number of cases of instincts that are protective. 

 If, for example, a flock of young pheasants is suddenly dis- 



