308 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1945 



tific research should be concerned in the postwar era and on which 

 special emphasis should be placed. Future sources of energy stood 

 third on the list. Its importance was surpassed, in the judgment of 

 these men, only by the analysis and study of human behavior and the 

 general field of medical problems. 



I shall not linger long on the second characteristic of plants so nec- 

 essary for the existence of other life on this planet; that is, their 

 ability to construct from simple and elementary substances types of 

 chemical compounds essential for animals. Their capacity for mak- 

 ing sugar from carbon dioxide and water, constructing amino acids 

 from inorganic nitrogen and organic-carbon compounds, and for 

 synthesizing vitamins enables us to live. Plants are able chemists and 

 there is no substitute for them. 



PLANTS AND RESEARCH IN SCIENCE 



It would seem perhaps appropriate to terminate a discussion of 

 the importance of the plant kingdom after having pointed out the 

 essential relation of plants to our sources of energy and the de- 

 pendence of all life on their existence. However, plants do more 

 than fill our stomachs, warm our bodies, and help us to go quickly 

 from here to there. For example, plants are useful for the inves- 

 tigation of problems in science. For this purpose they have cer- 

 tain advantages. They can be grown in large numbers, and we 

 have no compunction in destroying them in quantity if it is desirable 

 for the purposes of the research. Their firm, well-delineated cell 

 walls, general structure, and methods of reproduction make them 

 well adapted to the investigation of certain kinds of problems, and 

 their infinite variety in morphology and physiology offers oppor- 

 tunity to select an organism best fitted to serve as experimental 

 material for attack on a particular question. 



The study of plants played a major part in the development of 

 our knowledge of cells and the formulation of the cell theory. Cells 

 were first described by Robert Hooke in 1665 from charcoal, cork, 

 and other plant tissues. The discovery of the nucleus is generally 

 ascribed to Robert Brown, botanist, who made his announcement in 

 1831. The first careful description of cell division we owe to the 

 botanist Hugo von Mold, who introduced the term "protoplasm" in 

 its present sense. Chromosomes were figured by the botanist Anton 

 Schneider in 1873 and first adequately described by Strassburger 

 in 1875. 



In many other directions Ave find that research with plants has 

 led to fundamental discoveries. The investigations of Payen and 

 Persoz in 1833 on the diastatic activity of germinated barley opened 

 the door to the field of enzymes. Mendel's laws, the foundation of 



