THE MANTIS.— THE NEST 93 



the substance of the nest consists of cylindrical tubes, 

 having a curious tangled appearance, which are arranged 

 in two groups of twenty each. They are all filled with 

 a colourless, viscous fluid, which is precisely similar in 

 appearance in all parts of the organ. There is no indi- 

 cation of any organ or secretion which could produce a 

 chalky coloration. 



Moreover, the method by which the snowy band is 

 formed rejects the idea of a different material. We see 

 the two caudal appendices of the Mantis sweeping the 

 surface of the foamy mass, and skimming, so to speak, 

 the cream of the cream, gathering it together, and retain- 

 ing it along the hump of the nest in such a way as to 

 form a band like a ribbon of icing. What remains after 

 this scouring process, or what oozes from the band before 

 it has set, spreads over the sides of the nest in a thin 

 layer of bubbles so fine that they cannot be distinguished 

 without the aid of a lens. 



We often see a torrent of muddy water, full of clay in 

 suspension, covered with great streaks and masses of 

 foam. On this fundamental foam, so to call it, which 

 is soiled with earthy matters, we see here and there masses 

 of a beautiful white foam, in which the bubbles are much 

 smaller. A process of selection results from variations in 

 density, and here and there we see foam white as snow 

 resting on the dirty foam from which it is produced. 

 Something of the kind occurs when the Mantis builds 

 her nest. The two appendices whip the viscous secretion 

 of the glands into foam. The lightest portion, whose 

 bubbles are of the greatest tenuity, which is white on 

 account of its finer porosity, rises to the surface, where 

 the caudal filaments sweep it up and gather it into 



