INHERITANCE OF SEX IN MERCURIALIS ANNUA 
Cecil Yampolsky 
The conception that sex is inherited in strictly alternative fashion has 
been much strengthened by the prevalence in recent years of the Mendelian 
doctrine that all inheritance is alternative. None the less there has always 
been abundant evidence among the higher plants of mixed sexuality and 
of the occurrence of sex intergrades of all degrees. The widespread oc- 
currence of so-called polygamo-dioecism among the flowering plants has 
been too little considered by the students of the nature of sex and sex de- 
termination. The discovery of sex intergrades in animals and the theore- 
tical conceptions drawn from their study by Goldschmidt, Banta, and 
others is certain to lead to more careful consideration of these well-estab- 
lished facts of mixed sexuality in plants. There is coming to be more and 
more general agreement that sex characteristics are matters of inheritance 
in quite the same sense as are other anatomical and physiological charac- 
ters. The occurrence of dioecious species whose individuals are prevail- 
ingly but not absolutely male and female makes it possible to show con- 
clusively that each sex tends to propagate its like and that the doctrine 
that one or the other of the sexes must be heterozygous for a fixed sex 
determiner can have no significance for these types at least. 
Observations and Data 
In a preliminary report (1916) a brief summary of the work on my 
female cultures of Mercurialis annua L. was given. This paper deals with 
female, male, and monoecious cultures of M. annua. 
As described before, seeds of M. annua were collected by Dr. N. L. 
Britton at Harrington Sound, Bermuda, in September, 1912. From this 
seed one plant was raised, the original mother plant of my subsequent 
female cultures. The seed was sown some time in September, 191 3, so 
that when I undertook the problem I had at my disposal a vigorous plant, 
evidently predominantly female, growing in the propagating house of the 
New York Botanical Garden. I will designate this as plant A. At the 
time of my first observation the plant was two thirds of a meter in height, 
vigorous and bushy. 
As is well known from the work of Kriiger (1908), Bitter (1909), and 
Strasburger (1909a, 1909&), which I shall later discuss, M. annua produces 
plants which are purely male and purely female, as well as males and fe- 
males that produce varying numbers of seeds, the result of the sporadic 
appearance of sex elements of the opposite sex on the several plants. In 
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