30 



BULLETIN 1379, U. S. DEPARTMENT OF AGRICULTURE 



In contrast to the field experiments, however, the pot-culture trials 

 afford results from several similarly treated pots and plants, so that 

 an estimate of individual experiments may be made by comparing 

 the differences between treated and untreated plants with the prob- 

 able errors involved in the measurements. 



When the pot-culture records are examined in this way, it becomes 

 evident that the treated and untreated plants present substantial 

 differences. With uniform soil and seasonal factors for electrified 

 and control plants the association of these differences with the 

 treatment becomes intimate. The fact that these differences favor 

 the control plants about as often as the treated plants emphasizes 

 the complexities involved and makes one less certain that these 

 differences are definitely attributable to the electric discharge. 



The laboratory experiments of Blackmail and his associates have 

 been on the effect of a direct current of very low intensity on 

 the rate of growth of the coleoptile of barley. Differences in the 

 growth rate of treated and control plants were noted over short 

 periods. The small differences attributable to the direction of the 

 current and the pronounced after effects obtained make the inter- 

 pretation of the data difficult and uncertain. 



In general then, one finds in Blackmail's experiments many 

 significant differences between the electrified and control plants. 

 In some instances the relation of the discharge to these differences 

 may well be questioned. In others the relation appears to be an 

 intimate one, and the significance of such differences is the immediate 

 concern of further research in electroculture. 



Table 32. — Summary of elect roc alt ural trials 





1 k'finite influence reported 



Xo definite influence reported 



Method 



Year 



<>t. server 



Year 



Observer 



Soil-conducted currents: 



(18S9 



J1892 



11897 



1 1902 __ 



[1892 



<M903 



[1914 



1860 



H884 



(1844 



1916 



(1904 



1905-1911 



1913 



1914 



1917 



1876 



1878 



1910 



Warren 



1893 



1899 



1902 



1905 



1846 



Bruttini. 





Leicester 



Ahlfvengren. 





















Solly. 





















1883-87.. 



1907 



1909 



Wollnv. 





Iloldefleiss 



Gassner. 





Ross- 



Gerlach and Erlwein. 



Soluble plant food 



Modified atmospheric po- 

 tential gradient: 







Lemstrom. . 











1907 



1909 



1909-1910 



1910 



1911 



1918-1924 



1880 



1914 



Gassner. 







Gerlach and Erlwein. 



Increased potential 



Jtfrgensen, Priest ley, 

 Dudgeon. 



Blackman, Liverpool en- 

 gineers. 



Breslauer. 



Hostermann. 



Clausen. 



Briggs, Campbell, Heald, 



Flint. 

 Laikewicz. 



Decreased potential... 





Briggs and Shantz. 















A review of the literature of electrocultural experimentation up 

 to the present time does not lend assurance of great progress. (Table 

 32.) In 1800 Senebier {Jf.5) wrote substantially as follows: 



