8 



THE IMPORTANCE OF PLANTS 



5. What group of scientists were first 

 responsible for the inxcstigations on 

 cells, nuclei and on cell division? 



6. For what are each of the following 

 men noted: Robert Ilooke, Robert 

 Brown, Gregor Mendel, Payen and 

 Persoz, and Stanley? 



7. What plant did Louis Pasteur do a 

 lot of work on and what was he in- 

 vestigating? 



8. List fifteen important plant products. 



9. Name some beneficial aspects of the 

 activities of microorganisms. 



Elmer Drew Merrill 



Plants and Civilizations 



Reprinted with permission of the publisher 

 from Scientific Monthly 43:430-439, 1936. 



"All flesh is grass," an ancient scrip- 

 tural saying, is essentially true, for as 

 all herbivorous animals are directly de- 

 pendent on plants, so, once removed, 

 are carnivorous animals dependent on 

 the vegetation, even as is man. To a 

 very large degree our present civiliza- 

 tion is based directly or indirectly on 

 plants, and its continuance, in ultimate 

 analysis, is definitely dependent on the 

 plant kingdom. These evident truths 

 are merely stated to explain or at least 

 to justify the caption, 'Tlants and 

 Civilizations." 



There is an interesting corollary be- 

 tween the development of the various 

 types of vegetation in past geologic 

 times and the t)'pes of animals charac- 

 teristic of each geologic period. In the 

 past, as now, the animals of each epoch 



were dependent on the available food 

 supplv, and at all times the vegetation 

 was the primary source. It was not until 

 after the modern types of vegetation 

 were developed, in the Cretaceous and 

 in the Eocene of the TertiarA', that the 

 mammals, the highest group of ani- 

 mals, could become dominant, al- 

 though they appeared in geologic time 

 some millions of ^'ears earlier. Previous 

 to the development of the grasses, the 

 chief t\'pe of plant that will thrive un- 

 der constantly heavy grazing, the food 

 supplv of the herbivorous mammals 

 was distinctly limited. The Eocene, the 

 oldest period of the Tertiar\', com- 

 monly designated "the dawn of the 

 recent," was the dawn of the recent 

 only in so far as the animal life was 

 concerned. Most of the modern types 



