RETROGRESSIVE METAMORPHOSES. 299 



Cases seem clearly to show that a barren and dry soil, as 

 well as a very dry atmosphere, are prominent causes for its 

 appearance. Thus Mr. Darwin described a double Gentiana 

 Amarella* growing " on a very hard, dry, bare, chalky 

 bank." T. S. speaks f of a double Fotentilla as "grow- 

 ing along a high wall, on a dry raised bank close to a 

 beaten path, adjoining a gravelly field." Again, a writer in 

 Gartenzeitung % alludes to the raising of double Stocks, and 

 says that they should only have " just enough water for 

 their preservation," and that " the starved state of the 

 plants " causes doubling. He alludes to Camellias, also, as 

 becoming double when grown in a dry soil. Kerria Jajponica 

 becomes double in Europe, in consequence of its missing the 

 wet season of Japan. It is well known that double flowers 

 are more easily raised on the continent than in England, 

 probably from a like cause, as our atmosphere is considerably 

 more charged with moisture than a continental one. In 

 raising double Stocks, it is customary to procure seed from 

 the flowers on axillary shoots which have a weaker repro- 

 ductive energy than those growing on the primary or central 

 axis, the seeds being smaller and often misshapen. The 

 above causes are, therefore, suggestive ; in that if a some- 

 what elevated, dry, and poor soil, one devoid of phosphates, 

 etc., be provided, the probability is that petalody will ensue. 

 Having once shown a trace of the malady, florists know how 

 to proceed in order to propagate and transmit the affection. 



There remains one other floral metamorphosis, and that 

 is of petals into sepals. This condition approximates to 

 virescence of the corolla, so that in many cases such a 

 change could scarcely be called sepalody. But M. Godron 

 has shown that when Eanunculus auricomus appears to be 



* Gard. Chron., 1843, p. 628 f Ibid., 1866, p. 973. 



+ Ibid., 1886, p. 197. 



