368 GENETICS IN RELATION TO AGRICULTURE 
On one of the farms the same mutation has recurred several times. 
Hayes believes that these mutations cannot be explained as the result 
of accidental crosses. For in the large series of crosses that have been 
L 
Fie. 150.—The Stewart Cuban variety of tobacco, a very promising mutation. Plants 
from seed sown under glass in December and transplanted to the open in May were twelve 
to fourteen feet tall in September and had produced eighty leaves per plant. (From the 
Journal of Heredity.) 
made in the Connecticut station in no case have new forms exhibiting 
this tendency to indeterminate growth been obtained. 
Nilsson-Ehle discovered that in pure lines of oats occasional grains 
appear that are aberrant either in color or in morphological characters. 
The variations tested by him either bred true at once or after one or 
two generations practically all of the progeny would breed true for the 
Digitized by Microsoft® 
