INDEX 
Regeneration, 61 et seq. 
Regression, 107 
Resemblance, protective, 56 
Retrogressive mutation, 154 
Reversion on crossing, 202 ef 
Séq., 213 
Rivet wheat, 234 
Rosenberg, 254 
Rotifers, 47 
Rough Chaff, 235 
Rust immunity, 237 
Saunders, 209, 213 
Saxifraga hypnoides, 59 
Schull, Dr. G. H., 213 
Sea-urchin, 256 
Sedgwick, A., 75 
Selection, artificial, 44, 115, 
135 
natural, 42 et seq., 48, 121 
Selective fertilization, 209, 
274 
Sex, 221, 270 ef seq. 
Sexual selection, 62 
Shaw, G. B., 322 
Sheep, Leicestershire, 137 
Shirley poppies, 140 
Snails, 215 
Snakes, 37 
Species, 5 
idea of, 6 
Jordan’s, 9, 320 
Linnean, 7 
Spencer, Herbert, 22, 40, 47, 
65, 68, 122 
Spermatozoa, 245 
Spindle, nuclear, 250 
Spores, 257, 305 
Standard deviation, 98 
Statistics, 12, 81 
collection of, 86 
Stature, 90, 106 
333 
Sterility, 320 
Stocks, 213 
Strawberries, 171 
Strength of pull, 89 
of wheat flour, 234 
Structural characters, 
heritance of, 183 
Substantive variation, 131 
Sugar-beet industry, 135 
Survival of the fittest, 47 
Swamping effect of crossing, 
221 
Sweet-peas, 209 ef seq. 
Symmetry, 129 
Syrphide, 58 
in- 
Tactual discrimination, 66 
Tetrads, 259 
Thomson, J. J., 24, 127 
Throw-back, 154 
Tinged white, 211 
Tower, W.L., 155 
Treviranus, 30 
Trifolium pratense, 150 
Tschermak, 19, 190, 203 
Types, primary and 
ordinate, 125 
sub- 
Unicellular animals, 240 
Unit characters, 176, 220 
Usher, Bishop, 27 
Variability, acquired, 317 
correlated, 106 
genetic, 317 
coefficient of, 99 
Variate, 97 
Variation, 14 
continuous, 14, 82, 314 
et seq. 
discontinuous, 
310 eft seg. 
I4, 128, 
