A GENETIC STUDY OF PLANT HEIGHT IN 
PHASEOLUS VULGARIS.! 
By R. A. Emerson.2 
INTRODUCTION. 
It is now coming to be expected generally that crosses between 
plant races that differ in quantitative characters will be inter- 
mediate between their parents in Fi with respect to such charac- 
ters, that they will exhibit a wide range of variation in F2, and 
that from these F2 segregates the parent types and various in- 
termediate forms can be isolated in F3 or later generations. Over 
three years ago Emerson and East (1913) presented evidence that 
no less than 11 quantitative characters in Zea mays are inherited 
in this manner. In the same paper there were reviewed similar 
results of seven investigations having to do with some twenty 
quantitative characters in several distinct groups of plants. 
Some crosses between plants that differ much in size have 
seemed not to follow the behavior outlined above. Notable 
examples of this sort are crosses between tall and dwarf peas 
(Mendel 1865, Lock 1905, Keeble and Pellew 1910), between 
tall and dwarf tomatoes (Hedrick and Booth 1907, Price and 
Drinkard 1908, and Gilbert 1912), between tall and dwarf sweet 
peas (Bateson and Punnett 1908), between tall and dwarf beans 
(Mendel 1865 and Emerson 1904), and between tall and dwarf 
maize (East and Hayes 1911 and Emerson 1911). In all these 
cases perfect dominance of tallness over dwarfness in Fi and simple 
3-1 segregation in F2 have been reported. ^ 
The distinctness of these two classes of behavior with respect 
to what have seemed to be solely quantitative differences gives 
them a special importance. Interest in them is heightened by the 
fact that different quantitative characters of even the same plants 
are found to belong to the two distinct classes of behavior. 
Thus, size of seeds in beans belongs to the first class of behavior 
^This paper was written in approximately its present form early in 1913. 
The original manuscript has been modified slightly by the addition of data 
and by references (mostly in footnotes) to recent papers bearing upon the 
matter under discussion. 
2 Resigned September, 1914, to become head of the Department of Plant 
Breeding, Cornell University, Ithaca, New York. 
3 Other characters beside tallness and dwarfness are concerned in some 
of these cases, namely, erect and prostrate habit in sweet peas (Bateson and 
Punnett 1908) and stout and slender stems in peas (Keeble and Pellew 1910). 
