22 



INTRODUCTION. 



bristles on the soles of their feet, which give these creatures their 

 well-known power of running with great rapidity along vertical 

 walls or the ceiling of a room back downwards, without falling. 4 

 These hairs, like those described above, are nothing more than 

 specially developed casting hairs, for they originate in the same 



FlQ. 10. Structure of the Gecko's foot ; a, from above ; b, a toe with its clinging ridges, 

 from below, slightly magnified ; c, diagram of section through a toe, exhibiting the 

 ridges in section ; rf, a few of these, magnified, with their bristles ; e, four rows of bristle- 

 cells, much magnified ; /, two separate bristle-cells, more magnified. From Cartier. 



way as those, and assist in the process of casting (fig. 8, ). 

 The clinging hairs are absent in the embryo of the Gecko ; they 

 do not appear till the first casting, and assist in causing the 

 process ; this sufficiently proves that they were not primarily 

 destined to be used as organs for clinging, but have acquired 



