CONTENTS XV 
Pace 
Purpose and plan. 342 
General method . . . . 343 
Method of hybridizing maize. 344 
Method of hybridizing wheat 345 
Method of hybridizing alfalfa : 348 
Some of the difficulties attending hebrdia: Hon 350 
Conditions favorable for hybridization 351 
Species hybridization . : : 351 
Svalof method of creating opulent : 352 
CHAPTER XX 
UrtinizaATION or Hyprips In Plant BREEDING 
Introductory. . . eV is SPARS ee Eee Se Bek te SOO: 
Purposes of fy hr diention rae ed ee eee Peer OS 
Increased production in F; maize nobnds Se dh EA ate Sate H ae fae Hoar om, Ao 
Crossing inbred strains or biotypes... .........2.2.2.2... . 354 
Effect of inbreeding in strainsof maize... ............ . 855 
Method of comparing yields... . . . et a Eee eee OU. 
Crossing species, subspecies, varieties and Eerie Spesuie eee en EN oo Ae ore 
Superior qualities of first generation hybrids. ............ . 359 
Immediate effect of crossing on sizeofkernel ............ . 860 
Centralized seed corn production. ..........2.2.2.2.2.2.2. 2... 861 
A method of producing hybrid corn seed ............2.2.2.. . 861 
Application in other annual crop plants. ..........2..2..4. =. . 862 
Application in vegetatively propagated plants... ........... . 364 
Rapid growing timber and ornamental trees... . . 2... . 1... . 865 
CHAPTER XXI 
Motations IN PLuant BREEDING 
Introductory... . ee ee ee Oe se ee ea eet OOO 
Occurrence of Teh ERHaTTEY eee ee Ree eee teh indie (ye te tea ohn eee OOO, 
Mutationsun-cropaplantcme aisue en (set ees Moen se proses, hun eetie ss oO. G 
Mhecsearchstorm-mutationsiee awe erly sia ss Gee ae aes) se sese ar O 
Propagation of mutations... ....... 2... 2.22.65. 5.44... 872 
CHAPTER XXII 
GRAFT-HYBRIDS AND OTHER CHIMERAS 
Introductory. . . te eats 4 edd One aaa eae eg ees mee 
Definition of meee Tea be BON eee, hon Stee rar ae Beata 
Winkler’s tomato-nightshade tens tnde? a yatta PPO echt fi etc ae tater meter mien 
Baur’s investigation of anatural chimera... ............. . 378 
Other natural chimeras... ... . Eee ea art ee oe eS L 
Two categories of variegation .. . Re ene Poe eS AR OOL 
The physiological behavior of graft hybrids i tag sot ge wt gh cece otsgs ky Br oh) Ba ee 
Modification of one graft-symbiont by the other... . 2... . . . . . . 888 
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