1921] BRIEFER ARTICLES 405 
of the elements considered essential for normal plant growth. Wheat 
seedlings with shoots 8-10 cm. high and roots 10-12 cm. long were 
grown in solutions that lacked nitro- 
gen had developed a root system similar 
and equal in length to those obtained from 
cultures grown in tap water. The tops of 
the plants grown in the relatively nitrogen- 
free solutions gained only a few centi- 
meters in shoot length, but the root mass 
had attained a length of 60-70 cm. for the 
different cultures of the set. From these 
results it was concluded that stimulation 
of long root development of wheat seed- 
lings grown in tap water was related to 
the deficiency of nitrogen in that growth 
~medium. 
Two questions might be asked in refer- 
ence to the results obtained: (1) Can plant 
roots grow without nitrogen? (2) What 
constitutes the best root development of a 
wheat plant for its normal growth? As to 
the first question, the tests did not prove 
that the large root development obtained 
from wheat seedlings grown in tap water 
or in the prepared nitrogen-free solutions 
was due to the total absence of nitrogen, or 
that it would have been obtained in the 
total absence of nitrogen. Obviously some 
nitrogen was contained in the seedlings 
when they were set in these media. Pre- 
sumably less and less became available to MG. 
r—Culture to iit 
the growing roots as the plants grew older, grown in tap water for six 
however, as the small supply originally in ° 
the seed had to suffice for more and more 
tissue (chiefly roots) as the seedlings en- 
larged. Whether the supply was ever exhausted in the growing region 
of the roots is not known. 
in good nutrient solution for 
two weeks. 
