84 ELECTRICAL STRUCTURE AND 



to make contact at its base. This, however, is not small 

 as in the acorn, but extends to the whole of its posterior 

 part. The cup, however, as shown in Fig. 88, is not 



Jregative teadfrvm earth. 



Fig. 32. CLUSTER"OF;OB-NUTS. [Original photo.] 



continuous with the foliage, but is insulated from it by a 

 fibroid layer which separates it electrically from the 



negative terminal or lead. 



i ve cup 



fibroid insulating layer 

 fa u>kick leaves are attarf . -- 



Fig. 33. FOLIAGE AND CUP OF COB-NUT OPENED OUT. 



[Original photo.] 



A longitudinal section of the ripe nut reveals much of 

 interest. The secretion is only slightly acid, and insulation 

 is regained in this instance by the rapid exudation of a 

 wax-like secretion upon the cut surfaces. In the specimen 



