The Making of Species 



variety," writes De Vries (p. 228), " the flower is 

 suppressed, and the loss is attended by a corres- 

 ponding increase in the number of pairs of bracts. 

 This malformation results in square spikes, or 

 somewhat elongated heads, consisting only of the 

 greenish bracts. As there are no flowers, the 

 variety is quite sterile, and, as it is not regarded 

 by horticulturists as an improvement on the 

 ordinary bright carnations, it is seldom multiplied 

 by layering. Notwithstanding this it appears 

 from time to time, and has been seen in different 

 countries and at different periods, and what is of 

 great importance for us, in different strains of 

 carnations. Though sterile, and obviously dying 

 out as often as it springs into existence, it is 

 nearly two centuries old. It was described in the 

 beginning of the eighteenth century by Volckamer, 

 and afterwards by Jaeger, De Candolle, Weber, 

 Masters, Magnus, and many other botanists. I 

 have had it twice at different times and from 

 different growers." Similarly, the long-headed 

 green dahlia arose twice over some years ago in 

 the nursery of Messrs Zocher & Co. 



Further, the peloric Toad-flax (Linaria vul- 

 garis peloria) is, De Vries informs us, "known to 

 have originated from the ordinary type at 

 different times and in different countries under 

 more or less divergent conditions." And, as this 

 variety is wholly barren, it must in each instance 

 have had an independent origin. Lastly, the 



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