HETEROGAMY AND AUTOGAMY. 199 



requiring insect agency and self- fertilisation or autogamy; 

 as well as in the majority of flowers which are too incon- 

 spicuous to invite insects at all, or which never expand. The 

 series of such flowers terminates in perfect and pei'petual 

 cleistogamy. 



The first condition, or Protandry, does not now require 

 special discussion or illustration ; as it is the prevailing one 

 in most conspicuous flowers : though it must be distinctly 

 borne in mind that the exceptions are rare in which a flower 

 cannot fertilise itself at some period or other before it fades ; 

 even though a large order, as Orchideoe, may furnish many 

 examples. 



Protogyny may arise from several causes. Miiller has 

 mentioned about twenty species of plants irrespective of the 

 Grasses which are more or less decidedly protogynous ; and 

 what one notices is that many are Alpine species of genera 

 which have other species dispersed elsewhei-e that are homo- 

 gamous or protandrous. Thus AneTnone alpina is protogynous, 

 but A. Narcissifolia is protandrous. Ranunculus montanus, B. 

 parnassif alius, E. pyrencevs are all protogynous. These may 

 be compared with the smaller-flowered forms of JB. aquatilis 

 which are homogamous ; but B. flammula, B. acris, B. repens 

 and B. bulbosus are protandrous with the outermost stamens 

 only. Thus, this genus supplies a progressive series. Other 

 protogynous and mountain species are Bryas octopetala, 

 species of Saxifrage, as S. androsacea and S. muscoides, and 

 S. Seguieri : but Miiller found S. oppositifolia and S. tridac- 

 tylites to be sometimes feebly protandrous, at others proto- 

 gynous. On the other hand, S. rotundifoUa, 8. aizoides, etc. 

 are protandrous. Loiseleuria procumbens, Trientalis Europcea, 

 Bartsia alpina, Hutchinsia alpina, and Thalictrum, alpinum 

 are all protogynous. 



Secondly, a group of plants, the flowers of which have 



