192 BOTANICAL GAZETTE 
The Gramineae other than Zea, so far as studied, are also 
positively rheotropic. Triticum vulgare and Secale cereale were 
so determined by Jénsson, Hordeum vulgare and Avena sativa 
by Berg.. In my experiments all four of these species were 
treated as already described for other plants.. After the grains 
had been placed in the vertical position in sawdust, and there 
sprouted, they were secured in the vertical position, by meats — 
of strips of blotting paper and rubber bands, to the sides of 
wooden bars extending parallel with the diameter of cylindrical 
glass basins, and so placed that the lower ends of the graifs 
just met the contained water. Here the preparation rested til 
the roots had attained a length of one or more centimeters. — 
The revolution -was then started. At once the question arises® 
to how these roots should be judged; for, as is well known, the 
roots of the cereals grow out in a bunch of several to . 
till a considerable length is reached. The meth 
_ the most satisfactory was as follows: When a record ¥ 
made the observer sighted horizontally along the roy 
_ counting all roots positive whose apical portion | viated 
_ vertical plane in the direction against the stream, all p 
could be no objection to the method employ ed - 
the rheotropism of these plants. An error in call 
positively rheotropic that was only inclined agen 
_ because of its plagiotropic position would be coun” 
_ by calling a root a negative that was inclined 1m 
: direction, solely through its plagiotropism, pr oe 
4 OF individuals employed was large. The results ¥ e 
_ @ preponderance in favor of rheotropic response 
be no question of the fact. 
