The Wohurn Pot-Culture Experiments, 1910-11-12. 317 



dressings of lithium had been used. Towards the end of 

 February, 1910, there was a decided change visible, for whereas 

 the plants receiving the small amounts of lithium remained 

 green and seemed to show more chlorophyll activity than did 

 the control plots, the plants to which, on the other hand, the 

 heaviest applications of lithium phosphate had been given, 

 were turned quite yellow. On thinning out the plants in 

 March, 1910, there was also a clear difference between the 

 roots of the several sets, for, while the smaller application of 

 lithium ('002 per cent.) showed rather more development and 

 stronger growth, the higher amounts produced a stunted root 

 growth, with absence of fine root hairs, the leaf development 

 also being poor. The plants were carried on until harvest, the 

 usual measurements, weights, &c., being recorded. The chief 

 points of interest are : (1) That the small addition of lithium 

 (•002 per cent.) gave a slight increase in grain and straw as 

 compared with the untreated lots, this being represented by 

 the figures 115 and 113 respectively as against 100 for the 

 untreated ; the results as regards the intermediate amount 

 (•005 per cent.) were not altogether conclusive or satisfactory. 

 (2) That the heavy dressing ('01) reduced the yield of corn 

 and straw by fully one-half. 



Hence, lithium phosphate would seem to differ but little 

 from the other lithium salts tried, in regard to its stimulating 

 or its toxic influence. That is to say, up to -002 per cent, in 

 the soil lithium would seem to be stimulating ; above this it is 

 more or less toxic. 



2. Lithium Phosphate and Lithium Nitrate. 1911. 



In 1911 the experiment of 1910 with lithium phosphate 

 was repeated, and, as there had been uncertainty last time as 

 to the effect of ^005 per cent, lithium applied as phosphate, 

 this quantity was again given, as also ^0075 per cent., the 

 smallest application being slightly increased, too, viz., from 

 •002 per cent, to ^0025 per cent. Thus the several applications 

 were : — (a) ^0025 per cent., (h) '005 per cent., (c) ^0075 per 

 cent., (d) •Ol per cent. At the same time lithium nitrate 

 supplying lithium in the several proportions just stated was 

 also tried. 



The general arrangements were as usual, each experiment 

 being in duplicate and the lithium salts being intimately 

 mixed with the whole of the soil in a single pot. The wheat 

 was sown on December 3, 1910, twelve seeds being put in each 

 pot, and then subsequently reduced to six growing plants per 

 pot. At once it was seen that the lithium salts, one and all, 

 exercised a marked influence on the germination of the grain. 

 With the lithium phosphate or lithium nitrate in small amount 



