312 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1945 



are familiar plants incompletely investigated, but there are consider- 

 able areas of the earth botanically unexplored and thousands of species 

 of plants still unknown to science. Any one of them might become 

 as important to us as Penicillium notatum. 



I cannot close this discussion of the economic aspects of plants with- 

 out referring to their importance in disease and decay. It is not my 

 intention, however, to discuss bacteria, yeasts, and molds as causes of 

 disease in other plants and in animals and man, nor to elaborate on 

 their relation to decay except to call attention to the importance of 

 the fungi in rotting wood and cloth, molding food, short-circuiting 

 electrical instruments, and deteriorating optical equipment in the 

 Tropics. Although those of us who live in the Temperate Zone are 

 acquainted with the fungus rots of telephone poles, railroad ties, and 

 house timbers and the minor losses from mildewed curtains or moldy 

 food, we have little conception of the destructiveness of molds in the 

 moist Tropics. Their control is a matter of major concern. 



Another way in which plants contribute to our economic system is 

 through the association of micro-organisms in the formation of various 

 products, for example, cheese which depends upon the activity of the 

 lactic acid and other bacteria and various molds; beer, wine, and other 

 fermented liquids produced by yeast; sauerkraut, vinegar, soy sauce, 

 and many others less well known or desirable. Bacteria, yeasts, and 

 molds as we learn to know them better are increasingly used for pro- 

 ducing specific chemical compounds which are beyond the skill of the 

 laboratory worker or which can be made more cheaply by the micro- 

 organism. Alcohol, acetic aid, acetone, glycerine, citric acid, gluconic 

 acid, and riboflavin are some of these compounds. The most recent 

 and illustrious addition to this list is, of course, penicillin. 



"Botany," said Thomas Jefferson, "I rank with the most valuable 

 sciences whether we consider its subjects as furnishing the principal 

 substances of life to man and beast, delicious varieties for our tables, 

 refreshments from our orchards, the adornment of our flower-borders, 

 shade and perfume of our groves, materials for our buildings or me- 

 dicaments for our bodies." 



Jefferson wrote these words in 1814. Priestley had but recently 

 demonstrated that plants produce oxygen ; the uniqueness and impor- 

 tance of photosynthesis was still to be recognized; coal and petroleum 

 were still to be developed; vitamins and amino acids, the relation of 

 plants to them and their importance in animal nutrition were un- 

 known; rubber was a plaything; the relation of bacteria and molds to 

 disease and decay was still to be discovered and penicillin was a long 

 way in the future. Thomas Jefferson estimated the importance of 

 plants on the basis of the knowledge about them available in 1814. 

 What would he have said today ? 



