CHAP. VIII. VIOLA. 319 



last species; but no perfect ones were produced. Mr. 

 Scott informs me that in India it bears perfect flowers 

 only during the cold season, and that these are quite 

 fertile. During the hot, and more especially during 

 the rainy season, it bears an abundance of cleistogamic 

 flowers. 



Many other species, besides the five now described, 

 produce cleistogamic flowers; this is the case, accord- 

 ing to D. Miiller, Michalet, Von Mohl, and Hermann 

 Miiller, with V. elatior, lancifolia, sylvatica, palustris, 

 mirabilis, bicolor, ionodium, and biflora. But V. tri- 

 color does not produce them. 



Michalet asserts that V. palustris produces near 

 Paris only perfect flowers, which are quite fertile; but 

 that when the plant grows on mountains cleistogamic 

 flowers are produced ; and so it is with V. biflora. The 

 same author states that he has seen in the case of V. alba 

 flowers intermediate in structure between the perfect 

 and cleistogamic ones. According to M. Boisduval, an 

 Italian species, V. Ruppii, never bears in France " des 

 fleurs bien apparentes, ce qui ne 1'empeche pas de fruc- 

 tifier." 



It is interesting to observe the gradation in the 

 abortion of the parts in the cleistogamic flowers of 

 the several foregoing species. It appears from the state- 

 ments by D. Miiller and Von Mohl that in V. mirabilis 

 the calyx does not remain quite closed; all five stamens 

 are provided with anthers, and some pollen-grains prob- 

 ably fall out of the cells on the stigma, instead of pro- 

 truding their tubes whilst still enclosed, as in the other 

 species. In V. hirta all five stamens are likewise an- 

 theriferous ; the petals are not so much reduced and the 

 pistil not so much modified as in the following species. 

 In V. nana and elatior only two of the stamens properly 

 bear anthers, but sometimes one or even two of the others 



