23 



In tables IX. — XI. will be seen a duplicate of the first series, so far 

 ftstreatineat and varieties of seeds used are concerned, but in this series 

 the plants were allowed to grow for ninety-six hours, after which 

 measurements were taken of both radicles and hypocotyls. Essen- 

 tially these results correspond very cloiely with those in tables given 

 in the first series, but in special cases variations may be seen. 

 It will be noticed, although the same four Lcclanche cell battery was 

 used as in tables I. — IV., that the optimum strength of current is 

 between three and five centimeters, instead of seven and eleven as in 

 the first case. This is due to the batteries having become weakened 

 by too constant use, a fad which was readily noticed by the force of the 

 vibrations of the Wagner hammer. It will also be noticed that the 

 gain per cent in radicles, by use of electric current, is not so high 

 as in the first series. An average of the radicles of those lots of 

 seeds which received the optimum strength of current is 4.6(5 centi- 

 meters, while the normals give an average of 4.08 centimeters, or a 

 gain of 14.26 per cent, by treatment, a much lower figure than in the 

 first tables. This set-ms to show quite conclusively that the benefi- 

 cial effect of electrical stimulation, where applied but once, is very 

 marked at first, but as the plants become matured this effect is partly, 

 if not wholly lost. 



A comparison of the growths of the hypocotyls and radicles shows 

 thatthey both respond about alike to electiical stimulation. Although 

 the gain per cent is not so high in every case, with the hypocotyls as 

 the radicles, the}' follow in about the same proportion, and the optimum 

 . current is the same for both. An average of the lengths of the 

 hypocotyls in those lots of seeds which received the optimum 

 strength of current, gives 3.49 centimeters, while the normals give 

 3.11 centimeters or an increase of of 12.18 per cent by use of elec- 

 tricity, which is 1.55 percent less than the gain in the length of 

 radicles in the same lot of seeds. 



An average of the number of seeds germinated in the various lots 

 in tables IX. — XI. gives the following: 



Treated. 



. , r 24 hours, 13.33 



Average number -o , ' i- ,n 



•, * . - -1 48 hours, 1 < . 1 9 



seeds germinated < ^,. , ' ,o ^.> 



^ , , ^ . I /2 hours, 18.43 



m each lot in \ ar i io lo 



1^96 hours, 18.43 



These results do not show so high a gain by use of electricity as in 



the first series, but prove that at the end of 72 hours all the seeds 



that retained vitality would germinate. 



