III. Elementary species of cultivated plants. 63
Beets, apples, pears, clover, flax and coconut.

IV. Selection of elementary species. 92
Cereals. Le Couteur. Running out of varieties. Rimpau 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