BEES AND FLOWERS. 



478 



to ivacli the noctiir (at ikj, fiii". 1) \\w Ixv (D) strikes with liis 

 head the short sterile aiMU {ac) whieh aets as a sort of l(>ver to hrino; 

 >lowu the loii<i- arm with its poHen sac {(t) to cover his haelc with the 

 fertile dust. 'V\\\\s laden the l)usy workman (lies to anoth'.'r flower and, 



Fig. 1. — Flower of Salvia ojficinalis. (.From Cheshire: Bees and Bee-keeping.) 

 A. Yoiing flower, showing an atrophied pollen sac. B. Old flower, showing the stigma. C. 

 Young, longitudinal section. D. Same visited by a bee. E. Longitudinal section, V)aso of the 

 corolla tube, a fertile pollen sac; <(r sterile pollen sac; <■ connective which joins the two sacs 

 and which can oscillate in hi around the filament of stamen /; st style; ng nectary at base of 

 ovaries; ca calyx; co corolla. 



as he enters, l)riishes off some pollen on the projecting stigma (fit). 

 With the exception of the Salria eorcina, studied by Ogle and Dar- 

 win, all the sages are thus fertilized by the bees. 



Fig. 3. — Primula vulytiris. 



A. Flower with long style (st). B. Flower with .short style (.s/'i; .s s' stigmala; a o' stamens; 



o o' ovaries; py pg' grains of poll(>n. 



Among the primroses we find a much larger and more varied 

 class of plants equally adapted to cross fertilization by insects, but in 

 a" different manner. As illustrated in the Primula vulgaris (fig. 2) 

 there are among these plants two sorts of flowers: Some (B) in which 



