138 HETEEOSTYLED TKIMORPHIC PLANTS. Chap. IV.-> 



are considered, there are five distinct sets of males. 

 Two of the three hermaphrodites must coexist, and 

 pollen must be carried by insects reciprocally from one 

 to the other, in order that either of the two should be 

 fully fertile ; but unless all three forms coexist, two 

 sets of stamens will be wasted, and the organisation of 

 the species, as a whole, will be incomplete. On the 

 other hand, when all three hermaphrodites coexist, and 

 pollen is carried from one to the other, the scheme 

 is perfect ; there is no waste of pollen and no false co- 

 adaptation. In short, nature has ordained a most com- 

 plex marriage-arrangement, namely a triple union 

 between three hermaphrodites, — each hermaphrodite 

 being in its female organ quite distinct from the other 

 two hermaphrodites and partially distinct in its male 

 organs, and each furnished with two sets of males. 



The . three forms may be conveniently called, from 

 the unequal lengths of their pistils, the long-styled, mid- 

 styled, and short-styled. The stamens also are of unequal 

 length, and these may be called the longest, mid-length, 

 and shortest. Two sets of stamens of different length are 

 found in each form. The existence of the three forms 

 was first observed by Vaucher,* and subsequently more 

 carefully by Wirtgen ; but these botanists, not being 

 guided by any theory or even suspicion of their func- 

 tional differences, did not perceive some of the most 

 curious points of difference in their structure. I will 

 first briefly describe the three forms by the aid of the 

 accompanying diagram, which shows the flowers, six 

 times magnified, in their natural position, with their 

 petals and calyx on the near side removed. 



* 'Hist. Phys. dea Plantes und deasen Formen," 'Verhand. 

 d'Europe,' torn. ii. 1841, p. 371. des naturhist. Vereins fiir preuss. 

 Wirtgen,"Ueberi2/iftrttm salicaria Eheinl.' 5. Jahrgang, 1848, S. 7. 



