128 THE WONDER OF LIFE 



hundred birds are gathered in the morning in one stackyard. 

 This does not sound much like the insurgence of Ufe ! 



It must be pointed out, however, that the impression 

 we often get of the brittleness of hving creatures is apt to be 

 fallacious. Truly the more intricate of them have ex- 

 quisitely balanced organizations, with machinery that is 

 easily put out of gear, for the more parts there are, the 

 greater is the likeKhood of something going wrong, and 

 chemical complexity often involves chemical instability. 

 But the big fact is that life is tough. 



A boy whirhng a stick, a pigeon strutting on the ground, a 

 fortuitous contact between boy's stick and pigeon's skull, 

 and it is all over with the favourite bird. This is a trivial 

 instance of what in the course of life we have far too 

 many occasions to deplore, namely casualties. Socially, a 

 casualty means an accident for which no one in particular 

 is to blame ; it is put down to ' the hand of God '. Bio- 

 logically expressed, a casualty is a fortuitous and fatal 

 incidence, on a living creature, of forces to which it cannot 

 in any effective way respond. It is plain enough that if 

 the pigeon had only had the skull of an elephant, or a ram 

 for that matter, it would not have died from a slight ' con- 

 cussion of the brain ' induced by the schoolboy's carelessly- 

 handled stick. But then it would not have been a 

 pigeon, and could not have been a pigeon, for the real 

 answer to the apparent difficulty is that complex organisms 

 cannot be adapted to casual dangers, that they would be 

 unthinkably handicapped if they were. Therefore, when 

 we think of the terrible destruction in the fauna of the 

 Gulf of Naples after an eruption of Vesuvius, or the decima- 

 tion both on the shore and inland that follows an unusually 

 hard winter, we are forced to admit that we cannot expect 



