352 BOTANICAL GAZETTE [May 
Zea mays (a yellow dent variety) was abundantly employed in 
several experiments. The seedlings with primary and secondary 
roots present were suspended in the usual way along the diameter 
of several glass basins. The temperature varied from 21 to 24° 
in air, and the velocity ranged from 150 to 600™ per minute. 
The duration of each test was one week. Some hundreds of 
Secondary and many tertiary roots were present in the latter half 
of the week. The primary roots, as usual in this species and 
variety, contorted very badly; the secondary and tertiary roots 
grew without contortion, and nearly all became strongly posi- 
tively curved. Only two or three took a. negative course, and 
not more than seven remained neutral. 
The secondary roots of Fagopyrum esculentum were tested on 
ten seedlings which had their roots immersed in the water of @ 
revolving basin for 41% hours. The temperature varied from 
23 to 28", and the rate of flow ranged from 125 to 600™ per 
_ minute. There were fifty secondary roots 1% long or over. 2 
_ Of the secondary roots, fifteen became positive, four nega 
i tive, and thirty-one did not curve. Of the main roots, seven 
became positive, one became contorted, and two remained 
ht. 
From the Se ecnsine results one can barcly. gen 
| because the experiments are too few. Yet it is eviden " 
& the two. plants, Cucurbita pepo and Tropacolum majus, whose © 
oe Toots had been found insensitive, or but weakly responsiV ° 
_ theotropic stimulus, the secondary roots are insensitive # 
and that in the Fagopyrum esculentum, the secondary ~ 
as the primary roots are sensitive, but the former 
_ Sensitive than the latter. For the variety of Zea may: gage 
_ May be said that the main roots always contort so 9% 
water that their relations in rheotropism cannot be determ 
Other varieties of Zea mays (popcorn and those empleo 
oe Jénssen, Berg, and Juel) we know to be nore ” wy 
. aa the main root. The experiments here recor 
_ secor - and dees roots to be theotropic also. 
