PLANT BREEDING 317 
varieties thus produced have been selected and bred from, 
as described in Sects. 892, 394. 
396. How Hybrids are Artificially Produced. — Hybridiz- 
ing, or crossing, plants is sometimes an easy, sometimes a 
rather difficult, process. It is simplest in unisexual flowers, 
for example, in those of Indian corn. Here the «tassel ” 
is a cluster of spikes of staminate flowers and the “ ear” 
is a spike of pistillate flowers, each thread of the “silk” 
representing a stigma and style attached to an ovary (grain 
7 
Fie. 222. A Peach Flower prepared 
for Hybridization. 
‘ Ss 4 A, flower cut round for removal of the 
Yz stamens; B, longitudinal section of a 
flower showing level s, at which the 
H cross-section was made in A. 
of corn). In hybridizing corn it is only necessary to tie 
a paper bag over the ear before the silk appears, in order 
to keep off stray pollen, leave it covered until full grown, 
then remove the bag, dust the silk thoroughly with pollen 
from tassels of another variety of corn, and keep the ear 
covered until the silk is entirely withered. 
In most cases of hybridizing it is necessary to go through 
with about the following process: 
(1) Select the flower to be pollinated, before it opens 
or its own pollen is mature. If it is one of a cluster of 
