FUNCTION IN PLANT LIFE 43 



some evidence of their effect upon the onion when the 

 negative pole is applied to the root and the positive pole to 

 the foliage, and it should be worth while to experiment 

 with, say, five or ten volts similarly applied to a field of 

 several acres. 



Another point which should not be lost sight of is that 

 some plants suffer from chlorosis, the disease being due to 

 deficiency of iron. 



Now, while it is true that the atmosphere is positive and 

 the earth negative, it also seems that Nature seldom if ever 

 relies entirely upon the constant and unintermittent 

 maintenance of any single condition upon which life 

 depends, and it is quite possible, even probable, that 

 electrical generation goes on in the plant itself. Most, if 

 not all, plants contain iron, and all of them inspire oxygen ; 

 two elements which, in the presence of a suitable alkali 

 and this we know to be contained in the protoplasm are 

 capable of generating electricity. During periods of 

 drought the root-supply of current may, conceivably, be 

 cut off by non-conducting dry earth, and if that current is 

 necessary to the plant it would perish had it not any other 

 source of supply ; whereas so long as its protoplasm 

 remained in a fluid condition it would, with some measure 

 of independent generation, be better fitted to endure 

 hardship. Take, for example, the savoy cabbage. The 

 outer green leaves contain a comparatively large quantity 

 of iron (17 milligrams per 100 grams of substance), and 

 those leaves standing out from the closely-folded heart 

 of the plant would have the largest oxygen intake. It 

 would not be necessary for that process to extend through- 

 out the plant, because it could be continued from the outer 

 leaves by conduction and induction if for any time during 

 the twenty -four hours even the surface of the soil was 

 moistened, as by dew. 



According to Sachs, chlorosis in plants may be cured by 



