533 
Food Szcb stances for Plant Growth. 
Very little is known at present as to the nature and composition of 
these substances. The all-important practical point is that their existence 
and action have been proved. Unfortunately the active substance appears 
to be largely destroyed by chemical manipulations, and it is difficult to 
obtain sufficient to study its chemical constitution and properties. 
Cooper and Funk ( 7 ) were the first to show that the curative substance 
for beri-beri is precipitated by phosphotungstic acid from an aqueous 
solution of an alcoholic extract of rice polishings. Later Hopkins found 
that the active growth-substance in his experiments could be obtained from 
the phosphotungstic acid precipitate of proteid-free milk. Funk (8), by 
a complex fractionation of the phosphotungstic precipitate of anti-beri-beri 
substance, succeeded in isolating a substance melting at 233°C.,whichhe called 
vit amine, and which, in amounts of o*oa to 0-04 grm., cured polyneuritis in 
pigeons. This substance he considered to be of the nature of a pyrimidine 
base. Hopkins ( 9 ), however, states that the additions in his growth experi- 
ments were free from amino acids, purine, and pyrimidine bases. 
At present the only definite statement that can be made concerning 
these bodies is that they are similar in being precipitated by phospho- 
tungstic acid, and in being active in very minute amounts. It has been 
suggested that they belong to a new group of nitrogenous compounds, 
which exist only in small amounts in food materials, but are so extremely 
active that minute quantities are sufficient to supply the needs of the 
organism. 
As previously stated, the growth results obtained with a water extract 
of bacterized peat suggested that the peat might contain substances similar 
to these accessory food bodies. Water and sand cultures of wheat 
seedlings were therefore commenced to test this hypothesis. The first 
experiment was made to determine how far the phosphotungstic acid 
fraction of bacterized peat extract was effective in stimulating plant-growth. 
The bacterized peat was extracted with absolute alcohol in a shaking 
machine for three hours, and the extract evaporated to dryness in 
vacuo. 
The residue was taken up in distilled water, filtered, and to the filtrate 
sulphuric acid was added until the concentration of the latter reached 
5 per cent. A slight precipitate of humic acid was filtered off, and to the 
filtrate an excess of a 30 per cent, solution of phosphotungstic acid was 
added. The whole was then left to stand overnight, when the liquid was 
decanted off through a filter, the precipitate repeatedly washed with 
a 5 per cent, solution of sulphuric acid, and finally decomposed with an 
excess of baryta. The liquid was filtered off from the precipitate of barium 
phosphotungstate, and the filtrate, freed from the last traces of baryta by 
means of a very dilute solution of sulphuric acid, was evaporated to dryness 
in vacuo . From seven kilos of bacterized peat the amount of dry substance 
