COBBLER OR TAILOR? 65 



did not thus project through holes in the leaf, and that 

 when searching for such nests he always looked out 

 for this. My subsequent observations have tended to 

 confirm his statement. 



All this time the edges of the leaf that formed the 

 nest had been held together by the thinnest strands of 

 cobweb, and it is a mystery how these can have stood 

 the strain. However, before the lining was completed, 

 the bird proceeded to strengthen them by connecting 

 the punctures on opposite edges of the leaf with threads 

 of cotton. Her modus operandi was to push one end of 

 a thread through a puncture on one edge and the other 

 end through a puncture on the opposite edge of the leaf. 

 The cotton used is soft and frays easily, so that that 

 part of it which is forced through a tiny aperture issues 

 as a fluffy knob, which looks like a knot and is usually 

 taken for such. As a matter of fact, the bird makes 

 no knots ; she merely forces a portion of the cotton 

 strand through a puncture, and the silicon which 

 enters into the composition of the leaf catches the 

 soft, minute strands of the cotton and prevents them 

 from slipping. 



Every one must have noticed how brittle a dead leaf is. 

 This brittleness is due to the silicon which is deposited 

 in the epidermis of the leaf. When the leaf is green the 

 silicon is not so obvious; it is nevertheless there. Some 

 leaves take up more silicon than others ; grasses, for 

 example, contain so much that many will cut one's hand 

 if roughly plucked. I imagine that the tailor-bird usually 

 selects for her nest a leaf or leaves in which there is 

 plenty of silicon. Thus the bird does not make a knot 

 F 



