ELECTRICAL STRUCTURE AND 



d and b. It is, however, not improbable that instead of the 

 whole of d becoming conductive, only the part g illustrated 

 by Fig. 25 may so function. This is suggested by the 

 greater desiccated space between the membranes at that 

 point. But even in that event the only material differ- 

 ence, so far as I can see, would be that the tension of 

 e would be lower than that of d by reason of the larger 

 surface area ofV 



Prior to the completion of the insulating system the 

 conducting layer c seems to receive 

 charge directly through the stalk of 

 the pod. During such time, there- 

 fore, the part g, or the depression 

 marked h thereon (Fig. 26), would 

 probably be the point of contact. 



As regards the unusually elabo- 

 rate insulation of the pod and 

 seed of the horse-chestnut, it is 

 worthy of remark that the secretion 

 both of the white, pithy material 



and the seed substance is markedly acid, staining steel and 

 instantly turning litmus-paper red. Neither of the three 



Fig. 25. SECTION OF 

 HORSE-CHESTNUT SEED. 



Showing the final ap- 

 pearance of the mem- 

 branes d and b. 



[Original photo.] 



membrane d 



Fig. 26. HORSE-CHESTNUT SEED. [Original photo.] 



The part g occupies about one-third of the area of the membrane d f 

 h is a small circular depression upon g and is probably of the nature of 

 a contact before the insulation is completed. 



membranes, however, has any effect upon litmus-paper, 

 and, so far as I could determine, all are, as one would expect, 

 chemically neutral. 



