276 ANIMAL DEFENCES 



such as "precautionary measures" and "passive defence", the 

 defence is of purely unconscious kind, and has been determined 

 by evolutionary factors working irrespective of the will or know- 

 ledge of the animal. Even when an animal actively defends 

 itself against attack it does not follow that it has any clear idea of 

 what the aggressor is after, though it must be admitted that the 

 latter has more clearly-cut ideas on the subject. 



The following scheme will perhaps serve to illustrate the 

 main principles of animal defence in the limited sense indicated 

 above, and it will be followed by detailed description of illustrative 

 instances, though space forbids anything like a complete review 

 of the animal kingdom under each heading. 



I. PRECAUTIONARY MEASURES 



Under this heading will be grouped those various defensive 

 measures which tend to obviate attack altogether, and these fall 

 pretty naturally under (i) Bodily Characteristics, and (2) Mode 

 of Life or Habits. 



(1) BODILY CHARACTERISTICS. These may be considered in 

 so far as they result in (a) Inconspicuousness, and (fr) Conspicu- 

 ousness. The first is obvious and the other will be clear after 

 explanation. 



(2) MODE OF LIFE. Defence may be promoted by (a) Feeding 

 at favourable times, (b) Feeding in favourable places. 



Supposing, however, that attacks are actually delivered, their 

 intention may be frustrated by means falling under a second large 

 heading. 



II. RESISTANCE 



This may take the form of either (A) Passive Defence, or 

 else (B) Active Defence. 



(A) PASSIVE DEFENCE. This may be effected by (i) Bodily 

 Characteristics, or by (2) Special Habits, and not infrequently 

 both contribute to the efficiency of the resistance offered. There 

 is also (3) Fecundity as a defensive measure. 



(i) BODILY CHARACTERISTICS. Of these perhaps the most 

 important are (a) Unpalatableness and Indigestibility, 

 resulting from various peculiarities ; (b) Possession of 



