368 AMERICAN JOURNAL OF BOTANY [Vol. 9, 
Table i. Effect of Differences in Extent of Root Development of 
Wheat Seedlings upon Tillering 
Average of 10 cultures (5 seedlings per culture) grown 4 weeks in nutrient solution 
Length 
Length 
Weight 
Weight 
No. of 
of Tops 
of Roots 
of Tops 
of Roots 
Tillers 
(cm.) 
(cm.) 
(g.) 
(g.) 
per 
Plant 
Cultures grown in tap water 25 days 
after seedlings were set in corks 
II 
62 
0.19 
0.18 ■ 
54 
Cultures transferred directly to nutri- 
ent solutions at time seedlings were 
set in corks 
10 
12 
0.17 
0.045 
1.2 
It will be noted from the table that the cultures of large root develop- 
ment tillered much more profusely than did those cultures which did not 
have large root development at the time they were placed in the nutrient 
solution. The question may now be asked as to the cause of the profuse 
tillering in the one case and of its lack in the other. The answer seems 
to be that in one case the cultures absorbed a greater amount of nutrients 
from the solution than they did in the other case. The cultures of large 
root development absorbed a much larger amount of nutrient from the 
solution because they had a larger root area with which nutrients came 
in contact. The profuse tillering of these cultures with the large root 
development, therefore, may presumably be accounted for by the fact 
that the cultures took up more nutrient than was needed by the plants 
for the normal development of the individual shoots of the seedlings. 
The consequence was a great vegetative response in the form of tillers 
which arose from the root crown. The cultures with the small but normal 
root development, while they produced some tillers, nevertheless did not 
produce them in any way comparable in number to those produced by 
the cultures with large root development. Presumably because of the 
smaller root development in these cultures, an excess of nutrients was 
not absorbed by these seedlings, and the condition that made for the profuse 
tillering above stated did not prevail. Although the cultures of large root de- 
velopment tillered much more profusely in all the different nutrient solutions 
used than did those of relatively small root development, nevertheless the 
chemical properties of the nutrient solution itself, as indicated by different 
concentrations of certain salts used, were also an important factor that 
affected tillering. This was shown by the fact that cultures of similar 
root development differed in the number of tillers produced, depending 
upon the kind of nutrient solution in which the seedlings were placed. 
It seems that data obtained with these solution cultures show 
why good tillering was obtained with the soil cultures referred to in the 
papers cited. As stated, the soil used in that experiment was low in nitrogen, 
so that the conditions of the growing medium in respect to the paucity 
