xu 



Contents 



X 



— Interfering Factors — Fluctuational Forms — "Pure Lines." 



XIV. Miscellaneous Exceptional and Unconformable Phe- 

 nomena ......... 



Crosses breeding true without Segregation. Parthenogenetic or Apo- 

 gamic Forms. Hieracmm — Sexual Forms — Numerical Aberrations 

 - — Irregularities of Dominance — Alternation of Generations — Mater- 

 nal Characters in certain Seeds. 



XV. 



XVI. 



Biological Conceptions in the Light of Mendelian 

 Discoveries 



Nature of Units — Nature of Segregation — Moment of Segregation — 

 Differentiation of Parts compared with Segregation — Reversion and 

 Variation. " Bush " and " Cupid " Sweet Peas — Mendelian Segre- 

 gation and Species — Discontinuity in Variation — Mendelism and 

 Natural Selection. 



Practical Application of Mendelian Principles 



Meaning of Pure-bred — Rogueing — Raising Novelties — A Practical Ex- 

 ample — Unfixable Types — Technical Methods — Sociological Appli- 

 cation. 



164 



chapter page 



IX. Gametic Coupling and Spurious Allelomorphism . 148 



Pollen-Shape and Flower-Colour. Axil-Colour and Sterile Anthers — 

 Hooded Standard and Flower-Colour in Sweet Peas. 



X. Heredity and Sex ........ 



Evidence from Breeding Experiments. ^;7£'w/«— Sex-limited Heredity. 

 The Horns of Sheep — Colour-Blindness — Sex and Spurious Allelo- 

 morphism. The Currant Moth — The Cinnamon Canary — The Silky 

 Fowl — Aglia tau — Cytological Evidence — Summary. 



XI. Double Flowers ........ 



Miscellaneous Cases. Recessive and Dominant Doubling — " Hose-in- 

 Hose" Flowers — The Special Case of Double Stocks. 



■4i XII. Evidence as to Mendelian Inheritance in Man 



Normal Characters — Diseases and Malformations. Dominants — Sex- 

 limited Dominants — Recessives — Notes on collecting Evidence. 



XIII. Intermediates between Varieties and the "Pure 

 Lines" of Johannsen 



Intermediates as Heterozygous Forms — Subtraction-Stages of Dominants 



196 



205 



235 



245 



266 



291 



Appendixes ........ 



PART II. 



'^)\ Biographical Notice of Mendel 



2. Translation of the Paper on Hybridisation 



3. Translation of the Paper on Hieracmm . 

 Bibliography . ' . 



Index of Subjects 



Index of Authors 



307 



327 



335 



380 



387 

 403 

 411 



