THE HAUNTS OF LIFE 65 



mucus to enter ; but there is a quicker method. ' It finds 

 the flexible edge of the shell, then by contractions of its 

 foot breaks a piece away. The mucus of the foot is then 

 poured out in quantities, and this has some poisonous effect, 

 as the bivalve, while stiU untouched, ceases to respond to 

 the stimuU which ordinarily cause a smart closure of the 

 sheU '. If the shell is covered with rough decoration the 

 Murex finds the burglary more difficult. 



Infantile Mortality.— The shore is a ' congested dis- 

 trict ' ; the birth-rate is high ; the infantile mortality is 

 enormous. Under the ledges of the rocks and in the crevices 

 we find in abundance the neat little 

 vase-like cases, we may almost say 

 cocoons, which the dog-whelk {Pur- 

 pura lapillm) forms for its eggs. 

 They change from a light pink to Fig. 20.— Three egg- 

 a straw colour. Each is the scene J-^ °Dog-TS 

 of a tragedy. If we examine a freshly Purpura lapUlua, 



, J £ 1 ii. i -i , • fastened to the 



lormed vase we find that it contams rook. 



scores of eggs. Later on, we find only 

 about half a dozen embryos. What has become of the 

 majority ? Careful examination at intervals shows that 

 some of the eggs get the start of others in their development, 

 and that the leaders devour the laggards, and continue to 

 lead because they do so. The same is true in the egg- 

 capsules of the great whelk or ' Buckie ' {Buccintim 

 undatum) — cases reminding one of the fruits of hops, 

 cemented together into balls often the size of an orange, 

 or much larger. Inside each capsule there is the same 

 grim elimination — ^the survivors use their fellows as other 

 embryos use the yolk of the egg. There is no lack of 

 brutal frankness in some of Nature'g ways, ' so careful 



