28 SECRETS OF ANIMAL LIFE 
the social evolution of wasps is illustrated by some 
of the Diggers and Pompilids, where the mother 
makes for her larvee a larder of paralyzed victims, 
but has no further commerce with her brood. She 
quickly makes a store of preserved (indeed, living) 
flesh and has done with it. The second chapter 
is seen in some African Eumenid-wasps, in which 
the mother brings freshly-paralyzed victims from 
day to day as her hatched larva has need of them. 
There is more of a personal touch here, for the 
mother comes into intimate relations with her off- 
spring, and seems to know it as hers. The 
third chapter shows an abandonment of the paralyz- 
ing device, the poison not being used except in 
killing the naturally recalcitrant victims. The 
prey is more or less masticated into pap, the mother 
retaining a tithe for herself, and the result is laid 
beside the larva, whose mouth, it is very interest- 
ing to notice, has ceased to have much power of 
chewing. 
But some very curious features now come to 
light, that the salivary secretion of the larva be- 
comes greatly exaggerated, as sometimes happens 
in man; that it tends to overflow at the mouth; 
and that it is for the mother “ l’objet d’une recherche 
particuliére.”’ It is the sop that keeps the mother- 
wasp self-forgetful, corresponding to the look in a 
baby’s eyes that keeps a human mother from utter 
weariness. The nurture of a single larva, distributed 
over a considerable time, leaves the mother-wasp 
with the gift of leisure, and there are gradations 
