11)04.] 



PUBLIC DOCUMENT— No. 33. 



23 



for their full development. In transplanting, however, there 

 was little or no loam attached to their roots. We have 

 handled lettuce so extensively in our greenhouse that we 

 were familiar Avith its characteristic requirements, and usually 

 had on hand an am})le supply of material from which to 

 select. The strengths of currents in all lettuce experiments 

 where gravity cells Avere used are based on four daily records. 

 The minimum and maximum currents are also given in paren- 

 theses in all cases. In the copper and zinc electrode con- 

 nections the currents Avere recorded every three days and 

 the tables shoAv the averages obtained. 



Table VIII. — Showing the Effect of Current Electricity upon the 

 Growth of Lettuce (Laetuca saliva L.). Normal Plant takc?i as 

 the Standard at 100. 



[Duration of experiment, 31 days.] 



No. 



Treatment. 



Per Cent, 

 gained 



in 

 Weight. 



Normal, 



Direct current; cojiper plate elec- 

 trodes 



Direct current ; copper plate elec- 

 trodes, . . . ... 



Copper and zinc plate electrodes, . 



.54.22 

 60.62 

 47.53 



Total average weight, in grams : — 



Normal, 34.69 



Treated 53.50 



Total per cent, gained 54.22 



Table IX. — Showing the Effect of Current Electricity upon the Growth 

 of Lettuce (^Laetuca saliva L.). Normal Plants taken as the Stand- 

 ard at loo. 



[Duration of experiment, 42 days.] 



No. 



Treatment. 



Number 



of 

 Plants. 



Current. 



Milliani. 

 peres. 



Total 

 Weight, 



in 

 Grams, 



of 

 Plants. 



Average 

 AVcight, 



in 

 Grams, 



of 

 Plants. 



Per Cent, 

 gained 



in 

 Weight. 



Normal, 

 Direct current. 



Direct current 



Copper and zinc plate electrodes, 

 connected, 



.199 



(.10-. 35) 



.342 

 (.20-. 50) 



.296 

 (.05-. 60) 



681 



818 



816 

 725 



28.12 

 34.08 



34.00 



30.20 



21.19 

 20.91 

 7.39 



Total average veeight, in grams : — 



Normal 28.12 



Treated ^.73 



Total per cent, gained, ,.,.,,,,., ft. 30 



