58 RANUNCULACE^E. [CHAP. 



stigma. Fig 51 represents a young flower seen 

 from the front, and after the removal of the calyx ; 

 it shows the entrance leading to the nectary, in 

 which are seen the heads of two mature stamens, a' t 

 while the others, a a, are situated in a cluster below. 

 Fig. 52 represents a section of the same flower. 

 Fig. 53 represents a somewhat older flower, in the 

 same position as Fig. 51. In this case the stamens 

 have all shed their pollen and retired, while the stig- 

 mas st, on the contrary, have risen up, and are seen 

 projecting into the space m. Fig. 54 represents a 

 side view in section of this flower. Anthophora pilipes 

 and Bombus hortorum are the only two North 

 European insects, which have a proboscis long enough 

 to reach to the end of the spur of Delphinium elatum. 

 A.pilipes, however, is a spring insect, and has already 

 disappeared, before the Delphinium comes into flower, 

 which, in the neighbourhood of Lippstatt, appears to 

 depend for its fertilisation entirely on Bombus hor- 

 torum, though Boissier assures us that in France and 

 in the Alps it is visited by several other species. 



It will be seen that the Ranunculaceae offer very 

 remarkable differences in the manner of their adap- 

 tation to insects. Honey is secreted by the sepals 

 in certain Paeonies ; by the petals in Ranunculus, 

 Delphinium, Helleborus, &c. ; by the stamens in Pul- 

 satilla ; by the ovary in Caltha ; while it is entirely 

 absent in Clematis, Anemone, and Thalictrum. The 

 conspicuousness of the flower is due to the corolla in 

 Ranunculus ; to the calyx in Anemone, Caltha, and 

 Helleborus ; to both in Aquilegia and Delphinium ; 

 to the stamens in Thalictrum. The honey is in some 

 cases easily accessible, in others it is situated at the 



