535 
Food Substances for Plant Growth. 
liquid filtered off from the precipitate of barium sulphate, and evaporated 
to dryness in vacuo. The weight of dry substance obtained from the 
silver fraction from 7 kilos of bacterized peat amounted to 0*2452 grm., and 
since this also was made up for experiment into a solution containing the 
silver fraction from 10 grm. of peat per litre, this solution contained the 
dry substance from the silver fraction in the proportion of 0*35 part per 
million. This fraction was also tested concurrently with phosphotungstic 
acid fraction upon wheat seedlings. Fifteen seeds were germinated in each 
of nine pots, which were arranged in three series of three each. Series I 
was treated with complete food solution containing nitrogen, phosphorus, 
and potash, estimated as NH 3 , P 2 0 5 , and K 2 0 , in the proportion of 400, 
200, and 1,220 parts per million respectively. Series II was treated with 
a similar solution, containing in addition seventeen parts per million of the 
phosphotungstic fraction, and Series III with the complete food solution 
plus 0*35 part per million of the silver fraction. The pots were first treated 
one week after sowing the seed, and after that each pot received once 
weekly 100 c.c. of its food solution for seven weeks. At the end of that 
period the plants were washed, dried, and weighed, and after the gross 
weight had been taken, the plants were all dried in the steam-oven at 
ioo° C. until their weight was constant. 
The results are as follows : 
Series. 
I. Complete food .... 
II. Complete food plus phos- 
photungstic fraction 
III. Complete food plus silver 
fraction 
Table II. 
Gross weight Increase over 
0/45 plants. Series /. 
64*5 grm. 
96*8 grm. 50-0 % 
96-5 grm. 49*6 % 
Dry Weight. 
Increase over 
Series I. 
1 3 ‘ 348 0 grm. 
16*3818 grm* 
*27% 
I 5 * 7 I 4 8 g rm - 
* 5 T 7 % 
The silver fraction from the peat extract, corresponding with the 
‘ vitamine ’ fraction of Funk, having thus given results approaching those 
of the phosphotungstic fraction, a preliminary investigation was made to 
test its effect on the growth of wheat seedlings in water culture. Two sets 
each consisting of eighteen similar seedlings were carefully selected, each 
set being originally of equal weight, viz. 473 grm. Each set was divided 
for purposes of water culture among three similar bottles of 200 c.c. 
capacity, six plants being inserted through notches in the corks of each 
bottle, so that the roots dipped into the solution. The three bottles of 
Set I were filled with Detmer’s nutrient solution, made with pure salts in 
physiologically pure distilled water, in which the proportions of NH 3 , P 2 0 5 , 
and K 2 0 were 400, 200, and 1,220 parts per million respectively ; while 
those of Set II contained a precisely similar solution which had received in 
addition 0*35 part per million of the silver fraction of peat extract. The 
