THE RHEOTROPISM OF ROOTS 357 
ts but two that have been tested by others for 
mm, and twenty-one species that have never been experi- 
dwith before. In my own work and that of others, there- 
ur species have been used. Of these, twenty have 
sitively rheotropic, and fourteen have been found 
_ Rheotropism cannot therefore be said to be a general 
OF going experiments teach nothing more clearly than 
sitive species differ greatly in the degree of sensitive- 
stimulating water current. As with almost any other 
e Tesponse, one may arrange species in a series according 
theotropism. The twelve species of plants reported as 
bic by Jonsson, Berg, and Juel should all be accounted as 
Y or moderately sensitive as compared with five Cruci- 
Lea mays (everta Sturt.) as reported in this paper. 
tteen species found insensitive are distributed through : 
s, and the twenty sensitive species through | six, 7 
4 species in a a single a have } rape fed in 
‘al five species of the Gramineae are sens ‘ive, 
Leguminosae are sensitive and - onsitive 
of them 1 sensitive to the w 
