INCOMPLETE DICHOGAMY IN ZEA MAYS 181 
incompletely “Twn ames Still less will it apply to monoecious 
and dicecious plan Here there is no question of autogamy 
or self- Scitilisalion,. nite for this reason all hypotheses founded on 
the — m es es by dichogamy are futile. 
“We ca suppose, however, since the non- ee 
maturation of | a sexes is ‘a phenomenon which occurs in most— 
perhaps in all—plants, a ad contrivance so no ane rig 
eae dichogamy pro s hybridization in the firs t place, 
and then, only later, a  eiimnete cross- attilieation 4 in plants with 
moncecious flowers. 
“Tt is well known that all the plants of a species growing 
sam 
possible for the earlier plants of a species to provide pollen for the 
stigmas of later plants. This is certainly often the case, but it is 
also certain that the stigmas of the very earliest plant of a proto- 
gynous species can only be, and actually are, fertilized with pollen 
from another species which flowers rm ; thus the con- 
clusion one arrived at must remain una . 
made careful observation during rere two last seasons of 
several nhniiveds of plants of Maize of many varieties and breeds 
in many fields and in several districts of the Transvaai. In 
statement, quoted above, therefore needs modi nap 
of Nat egg bare which was in a particularly favourable 
c ation, twenty-five plants (75°75 per cent.) 
onditi n, ‘ 
were ay protandrous to os oa (24°24 per cent.) which were 
protogynous; the ay meer in the plot were either too young or 
entata, selected from an — a X indurata cross, in which 
the oruiaean form i - rec 
numbers seem to indie ate Mendelian proportions, pag 
this oo be neta moideiaal: especially as they are so few. 
seems ae however, that protandry may prevail in one of ths 
two parent varieties, and protogyny in the other. 
Another of the above quoted ee seems to call for com- 
ment, namely, that in monecious and cious cee” “there is 
no question of autogamy or self-fertilization, and for this reason 
hypotheses founded on the prevention of self-fertilization by 
dichogamy are futile”; the itali sorts are mine. In the case of Zea 
sp 
position of male and female ‘Afidiaestitionk is such that, given a 
still morning and a plant shedding pollen at the same time that 
the stigmas are receptive, it can scarcely fail to be self-pollinated. 
