Guests, Welcome and Unwelcome 213 



same stalk; whereas, leaving off at the top, she carries 

 pollen away to the lowest blossoms on the stem of another 

 plant. 



Such are a few, and only a few, of the many marvellous 

 provisions for insuring fertilization, for preventing self- 

 fertilization, for promoting cross-fertilization, and for 

 preventing the robbery of pollen and nectar by insects 

 which would not benefit the plant; and to conclude with 

 the words of Professor Asa Gray : 



"If these structures and their operations do not argue 

 intention, what stronger evidence of intention in nature 

 can there possibly be? If they do, such evidences are 

 countless, and almost every blossom brings distinct testi- 

 mony to the existence and providence of a designer and 

 ordainer, without whom, we may well believe, not merely 

 a sparrow, not even a grain of pollen, may fall." 



QUESTIONS FOR REVIEW 



1. What peculiarities have Alpine flowers and why? 



2. How do the different classes of tropical flowers secure 

 their insect visitors? 



3. How does the sphinx-moth fertilize orchids? 



4. What peculiarity has the bind-weed? 



5. In what islands is the lack of insect life made good by 

 humming-birds? 



6. What is the humming-bird's food, and how does he get it? 



7. Describe the peculiar habits of the arum. 



8. Why are ants and snails usually unwelcome visitors? 



9. By what means do flowers keep off their enemies? 



10. Why is the bee's method of visiting the foxglove 

 especially efficacious. 



