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 

 Reappearance of 



Primula acaulis 



crucifers. Zea 



Equisetum, Dipsacus sylvestris 



Tomatoes. 



630 



ancestral characters. 



umbellata. Bracts of 



Mays cryptosperma. 



torsus. 



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 



