Nov. 19, 1917 
Reactions of Phosphorus of Root of Turnip 
369 
phosphorus in its thickened root, even if the supply is insufficient to 
produce a full-sized plant. Inasmuch as the second year of this biennial 
is devoted to the production of seed, using as nourishment the root 
substance formed the previous year, a certain amount of inorganic phos¬ 
phorus may be a normal requirement. Turnips which have been stored 
still contain a large proportion of such phosphorus, but the authors have 
not ascertained whether this phosphorus supplies the early needs of the 
second-year's growth. 
As a result of a critical consideration of all the data, the authors feel 
that the determination of the total phosphorus in turnips may prove as 
satisfactory for indicating the relative amount of available phosphorus 
in the soil upon which the turnips grew, as a determination of inorganic 
phosphorus in the juice by any method which they have tried, although 
in many instances the differences are more marked by the latter deter¬ 
mination. 
SUMMARY 
In this paper is recorded work undertaken with the prime object of 
ascertaining whether the amount of any portion of the phosphorus of 
the turnip root is correlated more nearly than the total phosphorus with 
the relative amount available in soils. 
Preliminary indications were derived from the successive extraction 
of dried turnips with ether, alcohol, and 0.2 per cent hydrochloric acid; 
but, since it was next found that larger amounts of phosphorus could be 
extracted from fresh than from dried turnips, all subsequent observations 
were made on fresh turnips. 
Coincident with the introduction of phosphorus into a nutrient solu¬ 
tion in which turnips were growing, the appearance of “inorganic” 
phosphorus and the disappearance of starch were traced microscopically 
in the different tissues; whereas upon withholding phosphorus the dis¬ 
appearance of inorganic phosphorus and the appearance of starch were 
similarly observed. About four-fifths of the total phosphorus of fresh 
turnips was extracted with water. When the latter was acidulated, 
somewhat less was secured because of partial precipitation. 
Only a few per cent of the extracted phosphorus failed to pass through 
dialyzers. Different precipitants of inorganic phosphorus were tested 
as to their ability to recover phosphate added in a standard solution to 
the dialyzates. 
The phosphorus in the precipitate formed by adding acetic acid to 
turnip juice was not in phosphoprotein compounds. There was no 
phytin in the juice. The presence of a phosphatase was not shown. 
Although the proportion of inorganic to total phosphorus in turnips 
was frequently made larger by phosphatic applications to the soil in 
which they were grown, this was not always shown to be the case by 
such methods as were used. 
