SEX INTERGRADATION IN THE FLOWERS OF MERCURIALIS ANNUA 97 
In the three-carpeled flower I have not found the diversity of intergra- 
dation that I have described for the two-carpeled flower. Many of these 
three-carpeled flowers have been observed with a single stamen, some with 
two stamens, with three stamens, and with six stamens. The poHen when 
examined appeared to be perfectly healthy and normal. 
While continuing the observations on the above described conditions 
within the flowers of the so-called monoecious form, an even more striking 
intergradation of parts, namely pistillody of the stamens and staminody of 
the pistils, was noted. There were hundreds of flowers that showed such a 
condition. 
Botanical literature abounds with many illustrations of the transmuta- 
tion of pistils into stamens and of stamens into pistils. The texts on ter- 
atology give many illustrations. Without going further into the literature 
on this subject, I wish to cite the work of Haring (1894). He gives an 
elaborate series of drawings showing various transition stages of stamens 
into pistils and of pistils into stamens in Salix caprea L. and Salix cinerea L. 
To Haring this facility with which one sex organ is transmuted into another 
is an indication of the morphological equivalence of sex organs of the oppo- 
site sexes. 
In the flowers of Mercurialis under observation, most elaborate and 
varied transition stages appeared of stamens into pistils and of pistils into 
stamens. Because of the minuteness of the flower, the flower buds were 
removed and examined under a binocular microscope. Figure 8 represents 
a female flower with an anther sac growing from one side. As far as could 
be determined, the ovaries were normal. The pollen grains were for the 
most part plump and appeared healthy. Figures 9 and 10 are parts of a 
single three-carpeled hermaphroditic flower. The carpels appeared to be 
normal; the stamens showed transition stages into pistils. In one stamen 
(fig. 10) there was one anther sac, in a second one (fig. 9) one of the anther 
sacs was much reduced in size. There can be no doubt that these stamens 
had been partially transformed into female tissue, because they showed the 
white translucent stigmatic surface and the hairs, characteristic of the 
female flower. The anther sacs were yellow like those of the normal sta- 
mens. The pollen from each of the anthers appeared healthy. 
Figures 11, 12, and 13 are parts of a two-carpeled hermaphroditic flower 
with what appear to be two anthers. Figure 1 1 is evidently a transmuted 
stamen, showing the stigmatic tissue and the hairs of the female flower. 
There was no trace of an anther sac or of an ovary. It was completely 
sterile. The second stamen (fig. 13) had the characteristics of both the 
stamen and the pistil. It had two anther sacs of unequal size and the 
stigmatic character and hairs of the pistillate part of the flower. One of 
the carpels (fig. 12) had imbedded within its tissue an anther sac. The 
majority of the pollen grains in this sac were plump and appeared normal. 
This flower, then, showed both staminody of the pistils and pistillody of the 
stamens in a very marked degree. 
