Contents 



xvii 



Lecture Page 



Purple leaves. Celosia. Italian poplar. 

 Cactus dahlia. Mutative origin of Dah- 

 lia fistulosa, and Geranium pratense in 

 the experiment-garden. 



XXII, Systematic atavism 630 



Keappearance 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 brac- 

 teatum monopetalum. Desmodium 

 gyrans and monophyllous varieties. Pel- 

 tate 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 nutri- 

 tion. Periodicity-curves. 



XXVI. Asexual multiplication of extremes . . 742 

 Selection between species and intra-spe- 

 cific selection. Excluding individual 



