BODILY CHARACTERISTICS INCONSPICUOUSNESS 277 



Armour, as purely defensive arrangements may be broadly 



termed. 

 (2} SPIX IAL HABITS, such, e.g., as the Death-feigning Instinct, 



Rolling-up Instinct, &c. 

 (3) FECUNDITY as a means of defending the species. 



(B) ACTIVE DEFENCE. This employs the method of counter- 

 attack, and includes, among other things (i) Use of ordinary 

 AGGRI ssiYi; WEAPONS; (2) Use of actively DEFENSIVE WEAPONS, 

 such as stings, stink-glands, &c. ; (3) CO-OPERATION for defensive 

 purposes between members of a community. 



An attacked animal, however, may be unfitted to offer either 

 active or passive defence, or may reserve its resistance, and in 

 both these cases commonly endeavours to effect its escape. This 

 may be considered under a third main heading, i.e. 



III. RETREAT 



It is scarcely necessary to tabulate the various ways in which 

 this is effected by different forms. Many animals are possessed 

 of great running powers, others can burrow rapidly, and so on. 

 The existence of dwellings or refuges is often a great help to 

 retreat, which may also be assisted by various special devices. 



It must, of course, be understood that there are no sharp 

 lines of separation between animals which employ different modes 

 of defence, for some species may fall under more than one heading, 

 and even those which in the first instance attempt to retreat may 

 nevertheless offer a determined resistance should they be over- 

 taken by their foes, e.g. deer and poisonous snakes. 



I. PRECAUTIONARY MEASURES 



(i) BODILY CHARACTERISTICS. 



(a) Arrangements which bring about INCONSPICUOUSNESS. A 

 particular kind of animal may be possessed of peculiarities of 

 form or structure, or both, in virtue of which it harmonizes so 

 well with the surroundings that detection by an enemy becomes 

 a difficult matter. But to reap the full benefit of this a form so 

 protected must remain perfectly motionless, as the least movement 

 may at once destroy the illusion. And since movement is abso- 

 lutely necessary to the great majority of animals, the protective 



