942 
Journal of Agricultural Research 
Vol. XXXI, No. 10 
problem of sex determination in hemp as well as in other dioecious 
species of plants should be regarded with an open mind. The prob¬ 
lem is so intricate that it probably will be fully solved only through 
the close cooperation between the geneticist and the physiologist. 
SUMMARY 
There is a distinct vegetative and sexual dimorphism in hemp. 
The vegetative differences are the same for those plants which remain 
sexually pure and those which later produce some flowers of the 
opposite sex. 
The two sex types occur in approximately at a 1 : 1 ratio. 
Under certain conditions both sex types produce flowers of the 
opposite sex. The most decisive factor in bringing this change about 
is the relative length of day and night. 
When staminate and carpellate individuals are crossed, the progeny 
consists of staminate and carpellate in equal numbers. When the 
carpellate is selfed or pollinated with pollen from another carpellate 
type individual, the progeny are all carpellate. The seeds produced 
on a staminate plant give rise to both sex types. 
It is maintained that sex determination in hemp can be explained 
on a genetic basis, and that the inheritance is of the XY type. 
LITERATURE CITED 
(1) Blackburn, K. B. 
1924. THE CYTOLOGICAL ASPECTS OF THE DETERMINATION OF SEX IN THE 
dioecious forms of lychnis. Brit. Jour. Exp. Biol. 1: 413-430, 
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(2) CORRENS, C. 
1907. DIE BESTIMMUNG UND VERERBUNG DES GESCHLECHTES NACH NEUEN 
VERSUCHEN MIT HOHEREN PFLANZEN. 81 p., illus. Berlin. 
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1917. EIN FALL EXPERIMENTELLER VERCHIEBUNG DES GESCHLECHTSVER- 
haltnisses. Sitzber. K. Preuss. Akad. Wiss. 51: 685-717, illus. 
(4) - 
1922. GESCHLECHTSBESTIMMUNG UND ZAHLENVERHALTNIS DER GE- 
SCHLECHTER BEIM SAUERAMPFER (RUMEX ACETOSA). Biol. 
Centbl. 42: 465-480, illus. 
(5) Emerson, R. A. 
1924. A GENETIC VIEW OF SEX EXPRESSION IN THE FLOWERING PLANTS. 
Science (n. s.) 59: 176-182. 
(6) Kihara, H., and Ono, T. 
1923. CYTOLOGICAL STUDIES ON RUMEX L. II. ON THE RELATION OF CHROMO¬ 
SOME NUMBER AND SEXES IN RUMEX ACETOSA L. Bot. Mag. 
[Tokyo] 37: 147-149. [In Japanese, English r6sum6, p. 86.] 
(7) McPhee, H. C. 
1924. THE INFLUENCE OF ENVIRONMENT ON SEX IN HEMP, CANNABIS 
sativa l. Jour. Agr.-Research 28: 1067-1080, illus. 
( 8 ) - 
1924. meiotic cytokinesis of cannabis. Bot. Gaz. 78: 335-341, illus. 
(9) SCHAFFNER, J. H. 
1918. THE EXPRESSION OF SEXUAL DIMORPHISM IN HETEROSPOROUS 
sporophytes. Ohio Jour. Sci. 18: 101-125, illus. 
1919. complete reversal of sex in hemp. Science (n. s.) 50: 311-312. 
1921. INFLUENCE OF ENVIRONMENT ON SEXUAL EXPRESSION IN HEMP. 
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