XU CONTENTS 
Pace 
Avfactorsy stem Inistockse. 4 cera ee eet nee aetna ae nem OG 
diruncatetwinged! Drosophila; 2 4), - 2. 2) en es eee ELLOS 
The factor explanation of reversion. . . . basi, ab erg Ee ae AO) 
Darwin’s hybridization experiments with pigeons. . . ........... 171 
Factor analysis of plumage color in pigeons... ......... 2... . 172 
CHAPTER X 
Factor RELATIONS IN QUANTITATIVE INHERITANCE 
Introductory. . . . ee er ee ah Get a ee cy LG 
Meaning of acne hahene Pol me Meee pec oe eee Ripa i oes een. a DEY 
alleen wariiracesiecs <-acte,:mcpecgh oles komme evan ue Ct ne mr rm (ie 
Bush and cupid sweet peas . . . BOe Gis 2a oe Ge ee OH ve eT 
Other factor differences affecting size... ...3.......0¢24..177 
‘Eheicotton leahtiactor wr cae eae: 2 oe cee eee ee meee LO 
Corolla length in tobacco . . . cee eden 
Mathematical requirements of the malic Pactor iene Bee size Sifieties ance’. 2 9. 185 
Castle’s hooded rats . . . AO os, Chur als hee Wn oy ea ae eae a TEL 
Hypothesis of factor v poeple a DOA ee Ce ee ACRE ae Ae LO) 2 
Arguments for the multiple factor theory ................ =. 194 
CHAPTER XI 
INHERITANCE OF Sex AND RELATED PHENOMENA 
Introductory. . .. ee ce ee ee ee OG 
The Drosophila or XY ge of ecinhediaaes Ay en ori eee teas ee oe See RSLS 
‘Sexslinkediimbheritancese. sos sne.a ert ete eG 2 ee en we Of 
Non-disjunction in Drosophila... 2... 2... 198 
Secondary non-disjunction .. . a7 ee A, ok ee ae eee? (0 
Non-disjunction not due to a qanae a fanior Pe we: Se oe aoe ea Oe 
Bearing of non-disjunction on chromosome constitution of sex . . . .. . . . 204 
The WZ type of sex-mheritance . . 2. : . 3 ee ee ee Se oe ee 205 
Analogy between the two types .. . os he Gags Go We oy we oS ae POY 
Sex-determination in certain insects. . ............4..... =. 210 
Sex-determination in certain plants. . . ... . . Ei tn ae ee ly 
Secondaryisexual’ charactersinen. ae coce Neck ce teen ner eres cr enCy Meee miemera 204 
AY AY sso Keay URoy ev apdNMoy te AMA Ala eA Wels, AMG. og of eh Gree hu Sete 2 AEP 
Intersexual forms in Lymantria 216 
Analopouszcageun VODACCOMs ee me Gee ae ere emer s ee ecunere gS Ree meee ITISS 
Conclusion 218 
CHAPTER XII 
Species HypripizaTION 
Introductory . : a ene 219 
Genetic comipatean eit fexonomic Hints PET EAT ohh Serene eech Serre ke) 
Species hybrids in Antirrhinum . 220 
Species: hy brids:ini@avini <2 ce oy cy oe eee EE eS 2S 
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