278 BOTANICAL GAZETTE [APRIL 
of pollen tubes. All of these events which start the various 
processes of developmental selection are superior or at least equal to 
the equivalent initiatory processes of natural or artificial selection. 
Among the latter seed germination which, while it gives a fairly 
even start to many of the competitors, is a more variable process, 
easily modified by soil conditions or delayed and unequal germina- 
tion; it is slower and it is not usually as efficiently simultaneous 
as pollination or fertilization. 
Selection between vegetative parts is also initiated by the 
awakening of the buds in the spring, a process which may be more 
or less simultaneous and comparable with seed germination under 
the most favorable conditions. Birth and the hatching of eggs in 
animals is a process well fitted to initiate the competition of natural 
selection. It is apparent that the processes of fertilization, pollina- 
tion, and the liberation of sperms are all very superior means of 
beginning a selective process, and that there are only a limited 
number of these events in the life cycle of an individual. 
The second requirement, that the competition should take place 
under uniform conditions, is one in which developmental selection 
excels, while natural selection is very inefficient. Under the con- 
ditions of isolation in pure culture in artificial selection, the environ- 
mental conditions are made very uniform, but even here the 
conditions are not as isolated and insulated as they are within 
the ovule of the pine seed, or within the tissues of the stigma and 
style, where pollen tubes must carry on their competition. On the 
other hand, the external environment where natural selection 
occurs is exceedingly complex and diverse. 
The third requirement, that selection should measure equal 
merits, is also one in which natural selection falls far short of provid- 
ing the best possible mechanism. In the external environment 
not all of the competing individuals which are “saved” are required 
to go through exactly the same performance, at the same time, in 
the same place, and under the same conditions. So many and 
varied are the factors that might be used to determine survival, 
and so different are the responses of plants that might be made to 
them in obtaining survival, that the capacity for an equal perform- 
ance of the same task under similar conditions is not measured, 
