Studies of Selected Spermatophytes. 225 



of the bee on page 185.) Can other insects than bees 

 gather the nectar ? Would introrse anthers serve as well 

 as extrorse anthers in this flower? How are pollen and 

 nectar protected from the rain ? Are there specially 

 colored parts which might serve to guide insects to the 

 nectar ? Show in a longitudinal diagram how a bee would 

 necessarily become dusted over with pollen, how the 

 adjacent stigma is prevented from receiving it, and how on 

 entering another flower the stigma is quite certain to 

 become pollinated. 



Let the student see what he can add to or correct in the 

 following quotation from Sprengel's book (see the account 

 of his book on page 172): " Suppose now that a bumble- 

 bee becomes aware of a distant Iris xiphium which it has 

 not yet seen ; it flies to the flower, attracted by its exquisite 

 qualities. When near to the flower the bee sees that it 

 is indeed mostly violet, but that those three parts which 

 most project are blue and have a beautiful yellow spot in 

 the middle. So these three parts attract the special atten- 

 tion of the bee, not only on account of the afore-mentioned 

 facts, but also because it finds they are exactly the places 

 upon which it can alight ; therefore it comes down upon 

 one of these parts nearest to it. Now since the arched 

 sepal lies close against the style these appear to be a 

 single piece ; but since the bee knows the significance of 

 the yellow spot, — namely, that it indicates the place where 

 it must enter the flower, — it pays no heed to that appear- 

 ance but works itself in between the style and sepal. 



" Now nature, who found it necessary to close the flower 

 so that no raindrop could run into the nectary, has in this 

 case so arranged it that the trouble to the bee is somewhat 

 lessened ; namely, the style is stiff and immovable while the 

 sepal may be pressed downward easily, springing elasti- 



