OCCURRENCE AND INHERITANCE OF SEX INTERGRADATION IN PLANTS 3 1 
male plants must all dominate over the weaker male gametes. Such 
however, is not the case. In the female that produces sporadic male flowers 
there is no reason, on Strasburger's assumption, why the male gametes 
should not be of two kinds. Selfed females produce only female offspring. 
That means that the male-producing tendencies transmitted by all the 
pollen grains of the tetrad are dominated by the female-producing tendency 
of the egg. On Strasburger's assumption there must now be at least three 
strengths of pollen grains, if not four: two kinds produced by the male, 
one of which is subordinate in its sex-determining tendency to the egg, and 
two kinds (on a priori grounds) produced by the sporadic male flowers on 
the female. Then, too, there are two kinds of eggs instead of one kind: the 
egg of the female plant which dominates over the weaker male-producing 
tendency of the pollen grains, and the egg produced upon the male plants, 
which is dominated by the male-producing tendencies of both kinds of 
pollen grains, and is thus weaker than the eggs borne on the female plant. 
We reach here a conception, which the thus-far meager data on in- 
heritance in dioecious and polygamo-dioecious forms seem to bear out, 
namely, that there may he graded potencies in hath the gametes, the egg as well 
as the male gamete, of such forms. The work of Correns is especially signi- 
ficant. In his work on Satureja, Silene, and Plantago he brings out clearly 
that the more pronounced the sex of the individual the more marked will 
be its influence on the sex of its offspring. The normal appearance of sex 
intergrades (there are at least thirty degrees in Plantago lanceolata between 
pure female and hermaphrodite) is evidence in that direction. The be- 
havior of the females of Mercurialis in my cultures is interesting in this 
respect. The original mother plant produced 66 seeds and 50 offspring. 
The offspring in turn produced seeds varying in number from I to 238. 
The original mother plant produced eggs of varying potencies as evidenced 
by the variation in male flower and seed production of the offspring. It is 
quite natural that the eggs should have varied in their ability to transmit 
the seed-producing qualities of the mother as in other qualities. Although 
the offspring tended to be like the mother in the sense that they were pure 
females or predominantly females, they varied in their ability to produce 
male flowers and hence seeds. The fertilized egg that produced a female 
that during its life history produced no male flowers or seeds is different, 
whether it be qualitatively or quantitatively, from the fertilized egg that 
produced a plant that produced many male flowers and seeds. One can 
conceive gradations in the power to produce male flowers and seeds, be- 
ginning with eggs with zero potentiality and running thence all the way to 
those with the potentiality of plant no. VII (Yampolsky, 1919), which 
produced 32 male flowers and 230 seeds. 
The male cultures of Mercurialis annua, while they do not show the 
tendency toward intergradations as often as do the females, nevertheless 
bring out very clearly gradations in sex potency. 
