254 



INDEX OF SUBJECTS 



Primula sinensis, flaked 57 



Leaf-shapes 70 



new dominant in 92 



sterility in 236 



"Giants" 236 



Primula, species-hybrids 242 



Protective coloration 140 



Pyrrhulagra, local forms 120 



Python, twin-vertebrae 60 



Quiscalus, geographical races of . . . 156 



Rabbit, Angora 46 



colours of 93 



Incompatibility with hare 242 



Raimannia odorata, Macdougal's 



experiments on 226 



Rats, Variation in 248 



Recessives, origin of 90 



Reciprocal crosses, giving distinct 



results 105, et seq. 



Regeneration 70 



Repulsion no 



Reversal on Regeneration 77 



Rhamphocoelus, geographical forms, 



159, 184 



Rhinoptera, variation in jaws of . . 38 



Rhythm in repetition 69 



Ribs, variation of 68 



Rights and Lefts 57-58 



Ripples, analogous to segments 60, 66, 67 



regeneration of 79 



Rollers, geographical races of 160 



Ruff, polymorphism of male 28 



Salamandra, maculosa and atra 



182, 199, 203 



spotted and striped 207 



geographical variation of 208 



Segmentation, nature of 63 



simulated mechanically 64 



compared with rippling 65 



analogies with 68 



Segmentation of normally unseg- 



mented structures 38 



Selection, Natural, an insufficient 

 cause of definiteness of types, 



17, 134, 142 



Sempervivum 250 



Serial Homology, the true nature of, 



62, 66 



Setina, Alpine varieties 181 



Sex of Twins 44 



Sex-factors, possible coupling of . . . in 

 Sexual characters, variation in 1 19 et seq. 



Siamese twins 44 



Silky Fowl 84, 85 



Simocephalus, changed by environ- 

 ment 218 



Sinistral forms I33~4 



Situs transversus 43 



Skate's jaws, variation in 38 



Sloths, vertebral variation 68 



Species, conceptions of, 3, 94, 99, 240, 245 



allied, distribution of 185 



alternative uses of the term 245 



Specific difference, universality of . . 12 

 of organisms compared with 



those of inorganic materials, 15 

 failure of theory of Selection to 



explain 18, 134, 247 



Sphyropicus varius 149, 156 



Spilosoma lubricipeda, varieties of 181 



Zatima, Heligoland form 181 



Spinal nerves, segmentation of. ... 67 



Sporadic variation 131, 134, 248 



Squashes, polymorphism of 100 



Staphylococcus pyogenes, variation 



in 213 



Sterility of hybrids, in general .... 233 



in Lychnis hybrids 20 et seq. 



in crossing forms of Draba 243 



Significance of 244 



Self 238 



Stilt 234 



Stocks 84, 104, 113 



Striped varieties 57 



Substantive variation 84 



Subtraction-stages 93 



Supernumerary limbs 72-76 



Sweet pea, variation of 91 



sterile anthers in 237 



Symmetry compared with heredity 41 

 Symmetry of body approximate. . 78 



Syndactyly 47 



in foot 48 



Syntheticformulae.in nomenclature 94 



Taeniocampa, fixed and variable 



species 25 



Tamias, local forms of 132 



Tanagers, geographical races of . . . 159 



Teeth, variation in 67, 39 



Tephrosia consortaria and con- 



sonaria 137, 139, 140 



Tephrosia species, separated by 



season 119 



Terminal members, variation of . . . 68 



Thais rumina, local variation in. . . 27 

 Tolerance, persistence of diversity 



due to 17, 134 



Tomato, number of cells in fruit. . 46 



Transitional populations, rarity of, 165 



an example 178 



Tropaeolum, sterile anthers in. ... 237 



