Fertilisation of Scrophularia aquatica and S. nodosa. 389 



aggregated infloresceuces. But there is a large minority 

 where the inflorescence bears only one or very few flowers, 

 or where they are dispersed and scattered, in wliich the 

 dichogamy is proterogynous. Examples may be found 

 among the Eammculacece, Gei-aniacece, Bosaceoi, &c., whicli 

 do not depend on bees for cross-fertilisation. 



The proterandry of indefinite inflorescences is thus 

 closely associated with the ascending habits of bees, and 

 since this mode of floral visitation can be shown to be more 

 rapid and natural than a descending mode, it is obvious 

 the proterandry has been in such cases produced by the 

 particular mode of visitation, and not vice versa. But, on 

 the other hand, most flowers fertilised by flies, which 

 display no system or method in floral visitation are 

 proterogynous. These facts seem to point to this, viz., 

 that, as a rule, the primitive proterogynous condition of 

 auemophilous flowers has been retained in the transition 

 to insect-fertilisation, unless where it was detrimental, as 

 it would be in inflorescences fertilised by bees. It is not 

 detrimental in Scrophularia ; but it has no advantage over 

 proterandry, which would be equally effective, and there- 

 fore it seems probable that Scrophularia presents us with 

 the most primitive type of inflorescence in the order to 

 which it belongs. 



EXPLANATION OF PLATE XIII. 



Figs. 1-5. Front view of expanded flowers of SrropJudaria nodosa. 



Fig. \. Xewly opened flower, with style {p) still bent up and stigma 

 in the centre of the aperture of entrance ; n, lateral angles 

 of nectariferous collar; n\ nectar collected in the lateral 

 sulci; 8, starainode; ft, filaments of external stamens. 

 First or pistillate stage. 



Fig. 2. Unfertihsed flower with style projecting horizontally from 

 the mouth of the corolla. The two inferior stamens have 

 appeared. 



Fig. 3. Fertilised flower ■with style curved downwards so as closely 

 to clasp the lower lip. The two inferior stamens have 

 now come forward. First staminate stage. 



Fig. 4. Fertilised flower, with the two inferior stamens fully 

 exposed, and the external or second pair beginning to 

 appear. Intermediate between first and second staminate 

 stages. 



Fig. 5. External stamens fully exposed and lying above the hori- 

 zontally projecting internal pair. Second staminate stage. 



