PHYSIOLOGICAL PROCESSES IN PLANTS 43 



PROBLEM VII 



A study of cross-pollination and some of the means of 

 bringing it about. 



a. Adaptations in the Flower 



Method. Study the structure of a butter and eggs or similar 

 blossom, looking for any adaptations or fitness for cross-polli- 

 nation or fertilization. 



Observations. 1. Are the sepals of the same size and shape, 

 i.e. regular? 



. 2. How do the petals and sepals compare in number ? In 

 size and shape? Might the pollen that finally reaches the 

 stigma more* likely come from the same flower (Self-fertiliza- 

 tion) or from a different flower (Cross-fertilization or polli- 

 nation) ? 



3. See if you can make out the landing place of a bee should 

 it visit this flower for nectar or honey. 



4. Find the anthers and stigma. Can the pollen readily 

 reach the stigma without some outside aid ? 



Conclusion. Show how such a peculiar form of corolla fits 

 it more especially for the visits of bees. 



b. Adaptations in an Insect Agent 



Method. Study dried or alcoholic specimens of the bumble- 

 bee or honeybee. 



Note to the Teacher. In place of using the following questions it 

 may be well to try permitting the pupils to ask and answer their own 

 questions. In fact, this should be done wherever it seems feasible. 



Observations. 1. How many distinct regions has the body ? 



Note. These regions are known as the head, thorax, and 

 abdomen, in order. 



2. How many pairs of wings do you find ? Of legs ? To 

 what part of the body are they fastened ? 



