THE MANTIS.— THE NEST 95 



and the alternating series of open fissures ! We are lost 

 in the face of such a wonder. Yet how easily the work 

 is performed ! Clinging to the wire gauze, forming, so 

 to speak, the axis of her nest, the Mantis barely moves. 

 She bestows not a glance on the marvel which is growing 

 behind her ; her Hmbs are used only for support ; they 

 take no part in the building of the nest. The nest is 

 built, if we may say so, automatically. It is not the 

 result of industry and the cunning of instinct; it is a 

 purely mechanical task, which is conditioned by the 

 implements, by the organisation of the insect. The nest, 

 complex though it is in structure, results solely from the 

 functioning of the organs, as in our human industries 

 a host of objects are mechanically fashioned whose per- 

 fection puts the dexterity of the fingers to shame. 



From another point of view the nest of the Mantis is 

 even more remarkable. It forms an excellent application 

 of one of the most valuable lessons of physical science in 

 the matter of the conservation of heat. The Mantis has 

 outstripped humanity in her knowledge of thermic non- 

 conductors or insulators. 



The famous physicist Rumford was responsible for a 

 very pretty experiment designed to demonstrate the low 

 conductivity of air where heat other than radiant heat is 

 concerned. The famous scientist surrounded a frozen 

 cheese by a mass of foam consisting of well-beaten eggs. 

 The whole was exposed to the heat of an oven. In a 

 few minutes a light omelette was obtained, piping hot, 

 but the cheese in the centre was as cold as at the outset. 

 The air imprisoned in the bubbles of the surrounding 

 froth accounts for the phenomenon. Extremely refrac- 

 tory to heat, it had absorbed the heat of the oven and 



