16 ANIMAL LIFE AND HUMAN PEOGRESS 



a different way, long before man arrived at a comparatively 

 clumsy solution by the conscious exercise of his intelligence. 

 There is one Kttle human invention of a very trivial char- 

 acter which always interests me particularly in this connection. 

 Those of us who indulge in the pleasant vice of smoking are 

 familiar with a form of tobacco-tin possessed of two covers. 

 The inner one is hermetically soldered on. The outer one fits 

 on as a Ud in the ordinary way, but it is provided with an 

 ingenious little contrivance in the form of a sharp metal point 

 or cutter, capable of being so adjusted that when the lid is 

 twisted round the inner cover is cut through and can be 

 removed. This simple but effective device was anticipated, 

 millions of years ago, by that remarkable animal the tuatara of 

 New Zealand, a creature resembling a large lizard and interest- 

 ing to the zoologist from many points of view. This animal 

 lays eggs with tough, leathery shells, within which the young 

 tuatara develops until ready to hatch. How is it to get out 

 of the shell ? Well, it cuts a slit in it by means of a sharp 

 horny projection developed on the snout, which, having served 

 its purpose in a single action, is never used again and presently 

 disappears. 



Those of us who follow the progress of the great war — and 

 who does not ? — have lately heard a good deal about " camou- 

 flage." The term may be a new one but the idea has been 

 famihar to the zoologist for a great many years. Indeed, 

 himian attempts at camouflage are but feeble in comparison 

 with what has been unconsciously accomplished by many of 

 the lower animals. One of the commonest crabs of our own 

 shores nips off pieces of seaweed and dresses itself up in them 

 so as to bafHe the pursuit of its voracious enemies. In 

 Australian seas one of those curious fishes, the sea-horses, 

 improves upon this by growing imitation seaweed out of its 

 own skin. Various insects, as is well known, imitate twigs, 

 leaves, or even flowers, with the most artistic fidehty. The 

 cuttle-fish conceals itself on the approach of enemies by dis- 

 charging a cloud of ink into the water, just as we have recently 

 learnt to protect our ships from enemy attack by means of 

 smoke-clouds. 



