Species and Varieties, Their Origin by Mutation | Page 3

and Risler, Avena fatua. Meadows. Old Egyptian cereals. Selection by the Romans. Shirreff. Hays.
C. RETROGRADE VARIETIES.
V. Characters of retrograde varieties. 121 Seed varieties of pure, not hybrid origin. Differences from elementary species. Latent characters. Ray-florets of composites. [xiii] Progressive red varieties. Apparent losses. Xanthium canadense. Correlative variability. Laciniate leaves and petals. Compound characters.
VI. Stability and real atavism. 154 Constancy of retrograde varieties. Atavism in Ribes sanguineum Albidum, in conifers, in Iris pallida. Seedlings of Acacia. Reversion by buds.
VII. Ordinary or false atavism. 185 Vicinism or variation under the influence of pollination by neighboring individuals. Vicinism in nurseries. Purifying new and old varieties. A case of running out of corn in Germany.
VIII. Latent characters. 216 Leaves of seedlings, adventitious buds, systematic latency and retrogressive evolution. Degressive evolution. Latency of specific and varietal characters in wheat-ear carnation, in the green dahlias, in white campanulas and others. Systematic latency of flower colors.
IX. Crossing of species and varieties. 247 Balanced and unbalanced, or species and variety crosses. Constant hybrids of Oenothera muricata and _O. biennis_. Aegilops, Medicago, brambles and other instances.
X. Mendel's law of balanced crosses. 276 Pairs of antagonistic characters, one active and one latent. Papaver somniferum. [xiv] Mephisto Danebrog. Mendel's laws. Unit- characters.
D. EVERSPORTING VARIETIES.
XI. Striped flowers. 309 _Antirrhinum majus luteum rubro-striatum_ with pedigree. Striped flowers, fruits and radishes. Double stocks.
XII. "Five leaved" clover. 340 Origin of this variety. Periodicity of the anomaly. Pedigree- cultures. Ascidia.
XIII. Polycephalic poppies. 369 Permanency and high variability. Sensitive period of the anomaly. Dependency on external conditions.
XIV. Monstrosities. 400 Inheritance of monstrosities. Half races and middle races. Hereditary value of atavists. Twisted stems and fasciations. Middle races of tricotyls and syncotyls. Selection by the hereditary percentage among the offspring.
XV. Double adaptations. 430 Analogy between double adaptations and anomalous middle races. Polygonum amphibium. Alpine plants. Othonna crassifolia. Leaves in sunshine and shadow. Giants and dwarfs. Figs and ivy. Leaves of seedlings.
E. MUTATIONS.
XVI. Origin of the peloric toad-flax. 459 Sudden and frequent origin in the wild state. Origin in the experiment-garden. Law of repeated mutations. Probable origin of other pelories.
[xv] XVII. The production of double flowers. 488 Sudden appearance of double flowers in horticulture. Historical evidence. Experimental origin of Chrysanthemum segetum plenum. Dependency upon nourishment. Petalody of stamens.
XVIII New species of Oenothera. 516 Mutations of Oenothera lamarckiana in the wild state near Hilversum. New varieties of _O. laevifolia_, _O. brevistylis_, and _O. nanella_. New elementary species, _O. gigas_, _O. rubrinervis_, albida, and oblonga. _O. lata_, a pistillate form. Inconstancy of _O. scintillans_.
XIX. Experimental pedigree-cultures. 547 Pedigree of the mutative products of Oenothera lamarckiana in the Botanical Garden at Amsterdam. Laws of mutability. Sudden and repeated leaps from an unchanging main strain. Constancy of the new forms. Mutations in all directions.
XX. Origin of wild species and varieties. 576 Problems to solve. Capsella heegeri. Oenothera biennis cruciata. Epilobium hirsutum cruciatum. Hibiscus Moscheutos. Purple beech. Monophyllous strawberries. Chances of success with new mutations.
XXI. Mutations in horticulture. 604 Chelidonium majus lacinatum. Dwarf and spineless varieties. Laciniate leaves. Monophyllous and broom-like varieties. [xvi] Purple leaves. Celosia. Italian poplar. Cactus dahlia. Mutative origin of Dahlia fistulosa, and Geranium praetense in the experiment-garden.
XXII. Systematic atavism. 630 Reappearance of ancestral characters. Primula acaulis umbellata. Bracts of crucifers. Zea Mays cryptosperma. Equisetum, Dipsacus sylvestris torsus. Tomatoes.
XXIII. Taxonomic anomalies. 658 Specific characters occurring in other cases as casual anomalies. Papaver bracteatum monopetalum. Desmodium gyrans and monophyllous varieties. Peltate leaves and ascidia. Flowers on leaves. Leaves. Hordeum trifurcatum.
XXIV. Hypothesis of periodical mutations. 686 Discovering mutable strains. Periods of mutability and constancy. Periods of mutations. Genealogical trees. Limited life-time of the organic kingdom.
F. FLUCTUATIONS.
XXV. General laws of fluctuations. 715 Fluctuating variability. Quetelet's law. Individual and partial fluctuations. Linear variability. Influence of nutrition. Periodicity curves.
XXVI. Asexual multiplication of extremes. 742 Selection between species and intra-specific selection. Excluding individual [xvii] embryonic variability. Sugar-canes. Flowering cannas. Double lilacs. Other instances. Burbank's method of selection.
XXVII. Inconstancy of improved races 770 Larger variability in the case of propagation by seed, progression and regression after a single selection, and after repeated selections. Selection experiments with corn. Advantages and effect of repeated selection.
XXVIII. Artificial and natural selection. 798 Conclusions. Specific and intra-specific selection. Natural selection in the field. Acclimatization. Improvement-selection of sugar-beets by various methods. Rye. Hereditary percentage and centgener power as marks by which intraspecific selection may be guided.
Index 827
[1] A. INTRODUCTION
LECTURE I
DESCENT: THEORIES OF EVOLUTION AND METHODS OF INVESTIGATION
Newton convinced his contemporaries that natural laws rule the whole universe. Lyell showed, by his principle of slow and gradual evolution, that natural laws have reigned since the beginning of time. To Darwin we owe the almost universal acceptance of the theory of descent.
This doctrine is one of the most noted landmarks in the advance of science. It teaches the validity of natural laws of life in its broadest sense, and crowns the philosophy founded by Newton and