THE RHEOTROPISM OF ROOTS Igl 
4. Plants with a high degree of sensitiveness. 
: It has already been stated (p. 183) that in 134 individuals of 
_ four large-fruited varieties of Indian corn so many primary roots 
grew contorted in water that these plants are wholly unsuited 
_for experiment. At the same time it 
ts to be remembered that Jonsson, 
Berg, and Juel have found Zea mays 
theotropic, though none of them states 
the variety used. 
if instead of the large-fruited varie- 
ties of Zea mays we experiment with 
| the dwarf Zea mays, with the white 
| Seats shall soon find this variety 
* Reve root highly sensitive to 
“current of water. Quite unlike the 
| _ “ontorted roots of the field and sweet 
a a og primary roots of the popcorn 
a re all grow straight in water. In 
ted ws seventy-nine seedlings in 
pees ot water of 25°™ to 1000™ 
see period 36 hours, and water 
3. Th 
Fic. 3.— Zea mays (popcorn). 
End view of a row of ten seed- 
lings after being in the water — 
stream for11hours. The gen- 
seedlings growing from @ 
size of the preparation, the eee 
