CHAP. H. THEIR INTELLIGENCE. 85 



Triangles of paper. Elongated triangles 

 were cut out of moderately stiff writing-paper, 

 which was rubbed with raw fat on both sides,, 

 so as to prevent their becoming excessively 

 limp when exposed at night to rain and dew. 

 The sides of all the triangles were three 

 inches in length, with the bases of 120 one 

 inch, and of the other 183 half an inch in 

 length. These latter triangles were very 

 narrow or much acuminated.* As a check 

 on the observations presently to be given,, 

 similar triangles in a damp state were seized 

 by a very narrow pair of pincers at different 

 points and at all inclinations with reference 

 to the margins, and were then drawn into 

 a short tube of the diameter of a worm- 

 burrow. If seized by the apex, the triangle 

 was drawn straight into the tube, with its 

 margins infolded; if seized at some little 

 distance from the apex, for instance at half 

 an inch, this much was doubled back within 

 the tube. So it was with the base and basal 

 angles, though in this case the triangles 

 offered, as might have been expected, much 



*' In these narrow triangles the apical angle is 9 34', and the 

 "basal angles 85 13'. In the broader triangles the apical angle is 

 19 Itf and the basal angles 80 25'. 



H 2 



