736 
DUNCAN S. JOHNSON 
flowers along the axis of the spike. They occur with equal fre- 
quency at the base, middle or tip of the spike. Finall}', it is pos- 
sible that the immediate cause of the failure of amicrosporangium, 
e.g., to develop in an}^ quarter of the anther is the absence of the 
necessar}^ nutritive or spore-determining material from this region. 
How such an unusual distribution of this substance may be 
brought about it is not easy to see, though it is perhaps no less 
understandable than the cause of the usual distribution which 
results in the formation of the four microsporangia in the normal 
stamen. 
Probably an^^ factor that disturbs the mechanism for the nor- 
mal process sufficiently may bring about the suppression or exten- 
sion of sporogenous cells. Such a disturbance of the normal move- 
ment of either nutritive, stimulative, or possibly of inheritance- 
bearing substances in the plant seems the most probable imme- 
diate cause of the phenomena here recorded for Piper betel. 
Moreover it seems evident that the change which occurs in this 
sex-determining or stamen-determining substance is progres- 
sive and quantitative. (See Morgan, '09, p. 336.) Whether this 
distribution of material is ultimately conditioned by external 
factors acting on the plant, must here, as elsewhere, be deter- 
mined by experiment. For an investigator working in a region 
where this plant can readily be brought to flower and fruit, it 
may be expected to yield results of great interest concerning the 
segregation of the sexes in this species, with a bearing on the 
problem of the distribution of sexes in angiosperms generally. 
SUMMARY AND CONCLUSIONS 
The distribution of flowers of Piper betel maj^ be either dioe- 
cious, monoecious, or monoeciously polygamous. The degree 
of development of the stamens and pistils often differs markedly 
in different flowers of the same spike, or even in different stamens 
of the same flower. 
The details of the development of the stamens and pistils of 
the perfect flowers are those usually found in angiosperms. An 
evanescent wall separates the two nuclei formed by the first 
