io8 LABORATORY PRACTICE CHAP, xxv 



V. These four kinds of evidence support the doctrine 

 called the doctrine of the metamorphosis of parts, which holds 

 that the flowering plant has only three kinds of structures, 

 root, stem, and leaf, and that it produces structures to do all its 

 work by altering (or modifying) one or more of these three 

 parts. We found this to be true in studying the bud scales 

 (Chapter VIII), Protection (Chapter X), Storage (Chap- 

 ter XI), Devices for Climbing (Chapter XII), Epiphytes, 

 Parasites, and Saprophytes (Chapter XIII), Insectivorous 

 Plants (Chapter XIV), Vegetative Reproduction (Chap- 

 ter XVI) ; and now we find that the complicated structures 

 necessary for seed reproduction form no exception. 



