The Mantis: her Nest 



one is a protection against the other; and 

 the ingenious physicist, had he wished, could 

 easily with the same frothy wrapper have 

 maintained the heat of a body in cold sur- 

 roundings. 



Rumford knew the secrets of the stratum 

 of air thanks to the accumulated knowledge 

 of his ancestors, his own researches and his 

 own studies. How is it that for no one 

 knows how many centuries the Mantis has 

 beaten our natural philosophers in the matter 

 of this delicate problem of heat? How did 

 she come to think of wrapping a blanket of 

 foam around her mass of eggs, which, fixed 

 without any shelter to a twig or stone, has 

 to endure the rigours of winter with im- 

 punity? 



The other Mantidae of my neighbourhood, 

 the only ones of whom I can speak with full 

 knowledge, use the non-conducting wrapper 

 of solidified foam or do without it, accord- 

 ing as the eggs are destined to live through 

 the winter or not. The little Grey Mantis, 

 who differs so greatly from the other owing 

 to the almost entire absence of wings in the 

 female, builds a nest not quite so big as a 

 cherry-stone and covers it very cleverly with 

 a rind of froth. Why this beaten-up en- 



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