320 The Wohurn Pot-Culture Experiments, 1910-11-12. 



These results have a most marked significance, and the more 

 so because of the confirmation they have received in the earlier 

 experiments. At the same time they cannot but be called very 

 striking, for, to take a single instance, who would have for 

 a moment imagined that the mere presence of •001 per cent, of 

 lithium in a soil would cause the produce of the untreated soil 

 to be raised from 100 to 192, or again, that tbe increasing of 

 the amount of lithium present by "001 per cent, would cause 

 a drop from 143 to 14 in the produce. It is clearly brought 

 out that lithium, in whatever form, must not be present to the 

 extent of "003 per cent., or the influence will be a toxic one, 

 this being more marked with the nitrate than the phosphate or 

 the carbonate. 



Again, it would seem that the stimulating effect is greater 

 with lithium nitrate than with any other lithium salts, and, 

 further, that, on the whole, the stimulation is greater the smaller 

 be the amount of lithium used. The results with lithium 

 phosphate and lithium carbonate show only sinall increases 

 orer the control (no treatment) lots ; the case is, however, 

 very different with lithium nitrate. 



It is also worthy of note that the plants grown with lithium 

 nitrate in small quantity showed the largest amount of tillering 

 and better root growth, also that, to judge from the greener 

 appearance of the foliage, chlorophyll activity and starch 

 formation were going on more freely. Lastly, it was found 

 that the grain produced w^as, as a rule, of more glutinous 

 nature where lithium nitrate exercised its stimulating effect 

 On the crop. 



The following general conclusions may, as the outcome of 

 these several years' investigations, be drawn as regards the 

 influence of lithium salts. 



1. That lithium, in the form of any of its salts, produces 

 a toxic effect if it is present in the soil to the extent of "003 per 

 cent., or above that amount. 



2. That the toxic effect is greater the more lithium there be 

 present, and that as between different salts of lithium, the 

 nitrate is the most toxic. 



3. That when present in the soil to an amount not exceeding 

 "002 per cent., lithium possesses a stimulating influence and is 

 no longer toxic in nature. 



4. That, while this applies to all salts of lithium, the nitrate 

 would seem to be the most stimulating salt, and to produce 

 the best results when present not in excess of "001 per cent, 

 lithium. 



5. That the action of lithium salts on vegetation is exerted 

 mainly in the early stage of the germination of the seed. 



