Manchester Memoirs, Vol. Ixvi. (1921) 13 



bound to follow any effort for advance, it is all the more 

 necessary that we should take steps which will involve change 

 only after carefully considering the cost ; this cannot be 

 estimated until we have so studied, to the best of our ability, 

 the life history of all living creatures, that we may gain some 

 knowledge of how far one depends upon another. Further- 

 more, any interference with what I have called the artificial 

 natural balance must be watched with an open mind. 



Let me illustrate this last point by a practical case. One 

 of the questions which has constantly puzzled those who were 

 framing laws for protection has been how far the taking of 

 eggs of the lapwing should be prohibited ; the usual conclu- 

 sion is that the lapwing is wholly insectivorous, using this 

 word in that wider sense which means invertibrate-ivorous, 

 and that therefore it should receive the fullest protection. 

 But two other interests are taken into consideration — the one 

 commercial, for the eggs are in demand in the market, the 

 other a matter of policy, the attitude towards the farmer and 

 his hands ; it is unwise to add restrictions which it is difificult 

 to enforce. Therefore, in most cases eggs may be taken up 

 to a certain date, but after that they are protected. But 

 supposing that full protection is granted to the bird, and it 

 increases, are we sure that increase is desirable ? The lapwing 

 may, when in its normal numbers, confine its attention to 

 certain food, say the larvae of root-eating moths, larvae of 

 phytophogous diptera and coleoptera, such as crane flies and 

 wireworms, or to the small molluscs which certainly do 

 damage. But does the bird confine its attention to these ? 

 Does it sagely examine and leave unmolested the larva of a 

 carnivorous beetle ? Can it, or indeed any bird which follows 

 the ploughman, distinguish between the grub of a cockchafer 

 and that of the fertilising dung beetle ? And if it could have 

 we any reason to suppose that it would leave the so-called 

 useful insect for our benefit ? And in particular, does it or 

 does it not eat earthworms, and if it does, is it doing us good 

 or harm? Darwin, the great earthworm's advocate, showed 

 the utility of this despised creature, but may we not have too 

 many earthworms ? It is an unsettled problem. Leave the 

 worm problem to the mole, some say ; but do we ? We 

 destroy the mole, yet not, if we are honest, because it devours 

 the worm but because it throws up unsightly and awkward 

 mounds, obstacles to tillage, or, in many instances, because it 

 has a pelt which has commercial value. But does not the 

 worm-devouring mole do exactly what the worm accom- 

 plishes, aerate and moisten the ground through its tunnels, 



