316 GENETICS IN RELATION TO AGRICULTURE 
form retained the other distinctive characters of its parent. Finally, 
as Boshnakian points out, similar sports have been secured among sexually 
produced progeny in other species of Nephrolepis. Thus it appears 
that these interesting and valuable ornamentals owe their origin to altera- 
tions in specific genetic factors, z.e., to factor mutations in vegetative 
reproduction. 
We have found that new varicties of cultivated plants may be arti- 
ficially produced in either of two ways, viz., by the discovery and pre- 
servation of mutations or by hybridization. Factor mutations occur in 
both sexually and asexually reproduced plants and frequently produce 
new forms of immediate economic value. Sometimes, however, the 
original mutation may be merely a starting point indicating the line 
along which selection must work. . There is always the possibility that 
subsequent mutations in the same direction, even though they be 
minute, will be taken advantage of by the breeder. In the creation of 
new varieties for special purposes hybridization must usually be employed. 
The success of breeders in combining the desirable qualities of several 
species in the best modern varieties of the rose suggests untold possi- 
bilities in this field of plant breeding. 
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