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'before, or not until some time after, the stigma has so matured as to be 

 ready for pollination. In the former case, as we may observe in the .common 

 garden nasturtium (Tropceolum majua), the pollen is all carried away by 

 insects by the time the stigma presents itself, so that if fertilisation be 

 •efiected it must be through the bringing of pollen from some other blooms 

 still shedding it. Insects arc the means which accomplish this, and to 

 secure their visits the blooms spread them a banquet. 



The wonderful mechanism developed by double-sex flowers to insure 

 their cross-fertilisation is shown in the following familiar and interesting 

 .illasti-ations. 



Salvia officinalis. Young Flower visited by a Bee. 



In the common sage {Salvia officinalis) both the stamens and the pistil 

 .aie of a very peculiar form, and the latter is not fully developed and ready 

 "to be fecundated until after the anthers of the same blossom have shed 

 theii pollen. The shape of the flower, and the mode in which the bee enters 

 it, are shown in the above figure, in which the tip of the still undeveloped 

 pistil is seen just over the back of the bee, which is forcing its way down 

 to the nectary through the stamens — not visible. 



The anthers are shown in the next figure, but on an enlarged scale. 



Stamens and Anthers. 



The anther-cells, instead of being close together, are at the two ends 

 •of a long connective, which is attached by a sort of pivot joint at about 

 •one-third of its length to the stalk of the stamen. The lower anther-cells 

 contain very Uttle pollen, sometimes none at all, while the upper ones are 

 fully developed as shown in the figure. "When the bee thrusts its head 

 into the tube, it presses against the lower cells and pushes them back ; the 

 connectives revolve on their axis, and the upper anther-cells are brought 

 ■down on the bee's back, the hairs of which brush off the pollen, which the 



