96 SOCIAL LIFE IN THE INSECT WORLD 



had prevented it from reaching the frozen substance in 

 the centre of the omelette. 



Now, what does the Mantis do ? Precisely what Rum- 

 ford did ; she whips her albumen to obtain a soufflee, a 

 froth composed of myriads of tiny air-bubbles, which will 

 protect the germs of life contained in the central core. 

 It is true that her aim is reversed ; the coagulated foam 

 of the nest is a safeguard against cold, not against heat, 

 but what will afford protection from the one will afford 

 protection from the other ; so that Rumford, had he 

 wished, might equally well have maintained a hot body 

 at a high temperature in a refrigerator. 



Rumford understood the athermic properties of a 

 blanket of air-cells, thanks to the accumulated know- 

 ledge of his predecessors and his own studies and 

 experiments. How is it that the Mantis, for who knows 

 how many ages, has been able to outstrip our physicists 

 in this problem in calorics ? How did she learn to sur- 

 <-ound her eggs with this mass of solidifying froth, so 

 that it was able, although fixed to a bough or a stone 

 without other shelter, to brave with impunity the rigours 

 of winter ? 



The other Mantes found in my neighbourhood, which 

 are the only species of which I can speak with full know- 

 ledge, employ or omit the envelope of solidifying froth 

 accordingly as the eggs are or are not intended to survive 

 the winter. The little Grey Mantis {Ameles decolor), which 

 differs so widely from the Praying Mantis in that the 

 wings of the female are almost completely absent, builds 

 a nest hardly as large as a cherry-stone, and covers it 

 skilfully with a porous rind. Why this cellular envelope ? 

 Because the nest of the Ameles, like that of the Praying 



