METAMORPHOSIS. 175 



Ritter v. Heufler saw a flower of the toadflax {Lin aria 

 vulgaris) in which all stamens, including the staminode, 

 were transformed into trumpet-shaped tubes. 



Velenovsky observed a remarkable flower of the 

 rock-cress {Arabis alyina) in which all the stamens 

 were changed into petals ; the pairs of stamens of the 

 inner whorl were represented each by a single petal, 

 so that here fusion, as well as metamorphosis, had 

 occurred (fig. 130). 



De Bary observed that, as a result of the attack of 

 the fungus Peronospora violacea, the stamens of the 

 scabioiis {Knautia arvensis)^ were changed into violet 

 petals. Double flowers of the soapwort {Saponaria 

 o-fficinalis) are caused by the presence of the smut- 

 fungus (JJstilago Safonarise). 



MoUiard found that petalody of the stamens in the 

 cowslip [Primula officinalis) was caused by the pre- 

 sence of the fungus Dematiwn in the roots ; that 

 'double-flowered plants of Sapoyiaria officiiialis were 

 infected in their rhizomes by the fungus Fusarium, 

 while single-flowered plants were devoid of it ; that 

 petalody in the lesser scabious {Scabiosa Columbaria) 

 was due to galls of Heterodera radicicola. He planted 

 normal plants in place of the uprooted anomalous one, 

 and next year its flowers became double, and had 

 fungus on the roots. He states that the association of 

 parasite and host would tend to be accentuated most 

 in cultivation. 



Many of the Laurine^ are apetalous, and, as Cela- 

 kovsky points out, this is due, not to their having lost 

 the corolla by suppression, but because they never had 

 one, as is proved by the fact that the four outer stamens 

 alternate regularly with the 2 + 2-merous perianth as 

 a whole. This view of the matter is strongly sup- 

 ported by Bichler's observation that not infrequently 

 in Laurus a corolla is present as a result of transfor- 

 mation of the outer whorl of four stamens. Here, 

 says Celakovsky, is a clear demonstration of how a 

 corolla comes into being. 



