The Mantis: her Nest 



caudal threads sweeping the surface of the 

 foamy mass, skimming, so to speak, the top 

 of the froth, collecting it and retaining it 

 along the back of the nest to form a band 

 that looks like a ribbon of icing. What re- 

 mains after this sweeping, or what trickles 

 from the band before it sets, spreads over 

 the sides in a thin wash of bubbles so fine 

 that they cannot be seen without the magni- 

 fying-glass. 



The surface of a muddy stream contain- 

 ing clay will be covered with coarse and 

 dirty foam, churned up by the rushing tor- 

 rent. On this foam, soiled with earthy 

 materials, we see here and there masses of 

 beautiful white froth, with smaller bubbles. 

 Selection is due to the difference in density; 

 and so the snow-white foam in places lies on 

 top of the dirty foam whence it proceeds. 

 Something similar happens when the Mantis 

 builds her nest. The twin ladles reduce 

 to foam the sticky spray from the glands. 

 The thinnest and lightest portion, made 

 whiter by its more delicate porousness, 

 rises to the surface, where the caudal threads 

 sweep it up and gather it into a snowy ribbon 

 along the back of the nest. 



Until now, with a little patience, observa- 

 157 



