82 HABITS OF WOKMS. Chap. II 



probable. Out of 121 petioles extracted from 

 burrows early in February, 68 were embedded 

 by tbe base, and 53 by tbe apex. On 

 February 5 all the petioles which had been 

 drawn into the burrows beneath a Robinia, 

 were pulled up ; and after an interval ot 

 eleven days, 35 petioles had been again 

 dragged in, 19 by the base, and 16 by the 

 apex. Taking these two lots together, 56 

 per cent, were drawn in by the base, and 44 

 per cent, by the apex. As all the softer parts 

 had long ago rotted off, we may feel sure, 

 especially in the latter case, that none had 

 been drawn in as food. At this season, there- 

 fore, worms drag these petioles into their 

 burrows indifferently by either end, a slight 

 preference being given to the base. This 

 latter fact may be accounted for by the diffi- 

 culty of plugging up a burrow with objects so 

 extremely thin as are the upper ends. In 

 support of this view, it may be stated that out 

 of the 16 petioles which had been drawn 

 in by their upper ends, the more attenuated 

 terminal portion of 7 had been previously 

 broken off by some accident. 



Triangles of paper. — Elongated triangles 



