C)2 J. W. SLATER, ESQ., F.C.S., F.E.S., ON 



part, may survive, because it has been deposited by the 

 mother in a less conspicuous place than the rest. One egg 

 may have perished, not from want of fitness, but because. 

 some ovivorons or parasitical insect visited the particular leaf 

 to which it was attached. Other causes might be mentioned 

 — accidental as far as man can judge — upon which the 

 quickening, or the death of an egg, may depend. Here, then, 

 there is no selection, no weeding out, but a destruction of a 

 number of individuals with as little reference to their 

 properties as if the question had been decided by lot. 



From the egg we pass to the larva. Here there are doubt- 

 less greater individual differences. It may be at once 

 admitted that one caterpillar may have keener senses to per- 

 ceive the approach of danger, greater agility in escaping, 

 more cunning in concealment, or an odour less attractive to 

 enemies than have others, and that it may thus have a greater 

 prospect of survival. But every observer knows that a vast 

 number of cases must occur in which chance alone can decide. 

 The quite accidental matter of position at some moment may 

 be of far greater consequence for the life of a larva than a 

 slight variation in any of the points just mentioned. 



No small proportion of the premature deaths occur also in 

 the pupa state, and here we have a return to the conditions 

 of the egg. Without any reference to attributes of their own 

 some pupas may have been discovered by birds, by moles, 

 hedgehogs, or the like, while others may by pure accident 

 have escaped. The condition of a lepidopterous insect from 

 the egg to its emergence from the chrysalis seems very much 

 like that of the inmates of a town under the infliction of a 

 heavy bombardment. It may perish or it may survive, 

 neither alternative depending so much on its peculiar 

 attributes as on the position which it occupies at some given 

 moment. 



From butterflies Ave pass to birds. In a work containing 

 much with which I am unable to agree, the author argues 

 that it is not the weaker and slower grouse on the Scottish 

 moors which chiefly fall victims to the falcon. The swiftness 

 of this destroyer is so vastly in excess of that oi the fleetest 

 grouse, that all relative differences in speed among the latter 

 1 >inls utterly vanish. The strongest winged and most vigorous 

 moorcock, if once espied on the wing by the enemy, has 

 practically no greater chance of escape than a feeble, sickly 

 bird. On the very contrary, the boldest and most energetic 

 grouse, which will be as a rule the healthiest, will fall victims 



