80 HABITS OF WOEMS. Chap. IL 



cent, by the apex. This anomaly was how- 

 ever readily explained as soon as the thick 

 basal part was examined ; for in 78 out of 103 

 petioles, this part had been gnawed by worms, 

 just above the horse-shoe shaped articulation. 

 In most cases there could be no mistake about 

 the gnawing ; for ungnawed petioles which 

 were examined after being exposed to the 

 weather for eight additional weeks had not 

 become more disintegrated or decayed near 

 the base than elsewhere. It is thus evident 

 that the thick basal end of the petiole is 

 drawn in not solely for the sake of plugging 

 up the mouths of the burrows, but as food. 

 Even the narrow truncated tips of some 

 few petioles had been gnawed ; and this 

 was the case in 6 out of 37 which were 

 examined for this purpose. Worms, after 

 having drawn in and gnawed the basal end, 

 often push the petioles out of their burrows ; 

 and then drag in fresh ones, either by 

 the base for food, or by the apex for plug- 

 ging up the mouth more effectually. Thus, 

 out of 37 petioles inserted by their tips, 

 6 had been previously drawn in by the 

 base, for this part had been gnawed. Again, 



