A Genetic Study of Plant Height in Phaseolus Vulgaris. 13 
from 0-10 per cent of undoubted crosses in the progenies or 
pure races grown in the garden. 
Crosses have invariably been made in the greenhouse during 
winter. The rather hot, dry weather of Nebraska makes it 
almost impossible to cross bean plants in the garden. The stamens 
are removed shortly before the flower bud is ready to open and 
pollen from another plant is applied at once. Occasionally an 
anther may be crushed in the process of emasculation and a 
grain of pollen thus comes into contact with the stigma of the 
same flower. Altho the stigma is always examined with the aid 
Fig. 2. — Individual plant-covers of cheesecloth used to guard bush beans 
against insect pollination. 
of a lens after the removal of the anthers, partial self-fertilization 
occasionally results. It almost never happens that the parent 
races are so nearly alike that such accidental fertilizations cannot 
be detected when the Fi plants are grown. Among Fi progenies, 
several plants apparently exactly like the maternal parent race 
have been tested thru two or three generations and in all cases 
have proved to be pure races. The records of all such plants 
occurring accidentally in Fi progenies have been discarded in 
preparing the data for this paper. 
When planted, the seed of a single individual plant or of the 
cross of two individuals is given a family number, which is 
entered on the record card and used on the stake label to mark 
