412 
CECIL YAMPOLSKY 
are found three-carpelled ovaries, each one of the carpels at maturity bear- 
ing one seed (fig. B). 
Figure i represents the usual appearance of the male elements on the 
female plant. The number of stamens ranges from 5 to 16. In such 
flowers no pistil or trace of a vestigial pistil has been observed. The 
pollen grains appear plump and healthy. 
Figure 2 shows stamens arising around the base of the ovary. The 
number of stamens varies from i to 6 for each ovary. The pollen appears 
plump and healthy. The pistils of such flowers proved to be functional 
and produced seed. Figure 5 shows a female flower with 3 stamens. 
Figure 3 represents a condition in which one half the flower is male and 
Text Fig. i. Diagrammatic arrangement of pistils and stamens. 
the other half female. The number of stamens in such cases varies from 
3 to 8. The pollen appears healthy and the one-celled ovary functional. 
Figure 4 represents an arrangement of staminate and pistillate ele- 
ments essentially like that in figure 3, with the addition of from i to 5 
stamens at the base of the pistil. The pollen of both groups of anthers 
appears healthy. The carpel is functional. 
Mercurialis annua shows its intersexualism through the appearance 
on a plant of a given sex of functional organs of the opposite sex. The 
appearance of flowers of the opposite sex upon a plant is not due to the 
degeneration of parts as in Plantago lanceolata and Satureja hortensis. 
Figure 3, which shows a sectorial arrangement of male and female ele- 
ments in a flower, illustrates the only case in Mercurialis annua in which 
substitution of floral parts occurs. Sex-intergradation in the female is a 
matter of the appearance of one or more male flowers or male elements in 
the manner just described. A comparison of plant no. VII, the female that 
produced the highest number of male flowers and seeds, and plant no. 247, 
the male plant that produced the highest number of female flowers and 
seeds, shows no outward tendency of either one of them to assume the 
appearance of a male or female respectively. Yet on the basis of sex of 
flowers produced, no. VII tends towards maleness and no. 247 tends towards 
femaleness. 
It is difficult to determine the proportion in numbers of male to female 
elements borne on a given plant. Unfertilized female flowers shrivel up 
within a short time and then fall off. None the less, the sex of a Mer- 
curialis plant can be determined within two weeks after the germination of 
the seed. The plant blooms from then on to the time of its death. The 
