LECTURE XXXVIII. 



EVOLUTION OF PLANTS. 



Prof. Douglas H. Campbell. 



It is a mistake to suppose that the study of evo- 

 lutionary problems must be confined to the animal 

 kingdom ; plants offer quite as many and equally 

 convincing proofs of the law of Evolution. 



The principal data are obtained from two sources- 

 palaeo-botany, i. e., the study of fossil plants ; and com- 

 parative morphology in its widest sense, that is, the 

 study of the structure of the plant in all its parts and 

 at all stages of its development. Embryology has 

 given here, as in zoology, the most important clues to 

 relationships. 



Biology, the science of living things ; not of animals 

 alone. Botany as truly a department of biology as 

 zoology is. 



The simplest living things neither plant nor animal. 

 Protista. 



Uniformity in the ultimate structure of all living 

 things. The perfect plant or animal all a nucleated 

 mass of protoplasm. 



Lowest forms of plants. Fission plants. Bacteria, 

 blue-green algae. These not closely related to the 

 higher plants. 



Volvocinea3 (green monads) probable ancestors of 

 the higher plants. Also seem related to the flagellate 



