xiv Contents 



Lecture Page 



posites. Progressive red varieties. Ap- 

 parent losses. Xanthium Canadense. 

 Correlative variability. Laciniate leaves 

 and petals. Compound characters. 



VI. Stability and real atavism .... 154 

 Constancy of retrograde varieties. Atav- 

 ism in Ribes sanguineum albidum, in 

 conifers, in Iris pallida. Seedlings of 

 Acacia. Reversion by buds. 



VII. Ordinary or false atavism .... 183 

 Vicinism or variation under the influence 

 of pollination by neighboring individ- 

 uals. Vicinism in nurseries. Purify- 

 ing new and old varieties. A case of 

 running out of com in Germany. 



Vlil. Latent characters 216 



Leaves of seedlings, adventitious buds, sys- 

 tematic latency and regressive evolu- 

 tion. Degressive evolution. Latency 

 of specific and varietal characters in 

 Dianthus caryophyllus spicatus, in 

 the green dahlias, in white campanulas 

 and others. Systematic latency of 

 flower colors. 



' IX. Crossing of species and varieties . . 247 

 Unisexual and bisexual, or species and 

 variety crosses. Constant hybrids of 

 Oenothera muricata and O. biennis. 

 Aegilops, Medicago, brambles and other 

 instances. 



X. Mendel's law of bisexual crosses . . 276 

 Pairs of antagonistic characters, one ac- 

 tive and one latent. Papaver somnif- 



