IMPORTANCE OF PLANTS — ROBBINS 309 



our understanding of heredity and genetics, were discovered by 

 experimenting with peas. The idea of hormones was first pre- 

 sented by the botanist Sachs in 1880. The essential nature of the 

 so-called minor essential mineral elements, for example, manganese, 

 copper, and zinc, was demonstrated by Bertrand and his coworkers 

 for the black mold Aspergillus niger considerably before their im- 

 portance in animal nutrition was recognized. The discovery of the 

 nature of virus diseases to which belong the agents responsible for 

 smallpox, yellow fever, influenza, poliomyelitis, virus pneumonia, 

 foot and mouth disease, hog cholera, rabies and many other afflictions 

 of man, animals, and plants began with experiments by Iwanowski 

 in 1892 on the mosaic disease of tobacco and was completed by 

 Stanley in 1935 by the isolation from tobacco afflicted with mosaic 

 of the active agent as a nucleoprotein of high molecular weight. The 

 influence of day length on reproduction was demonstrated for plants 

 by Garner and Allard some years before the correlation of repro- 

 ductive activity in animals and day length was investigated. 



Perhaps nowhere is the importance of work with plants for scien- 

 tific objectives of general application demonstrated better than that 

 which has been carried on with yeast. Pasteur's investigations on 

 fermentation contributed in a major way to the germ theory of dis- 

 ease and to his later discoveries in the field of medicine. Investi- 

 gations on the chemical changes induced in carbohydrates by yeast 

 have had an immense influence on our knowledge of respiration and 

 the intermediary metabolism of carbohydrates in animals, including 

 man. At least two vitamins, pantothenic acid and biotin, were 

 discovered from a study of yeast. 



Many other examples could be cited illustrating the importance 

 of research on plant material. What I have said, however, will suf- 

 fice to show that the study of plants has given us in the past, as 

 it will in the future, concepts of general significance in biology, a 

 knowledge of principles applicable to other living things, including 

 ourselves. 



RECREATIONAL VALUE OF PLANTS 



I scarcely need call your attention to the recreational value of plants. 

 The opportunity to enjoy flowers, shrubs, and trees acts as an antidote 

 for the artificiality and tension of city life, relieves the drabness and 

 monotony so frequently associated with existence in a small town or 

 in the country, and satisfies a deep-seated desire in all of us. It can- 

 not be expressed in units of value, though it has been recognized in art, 

 poetry, architecture, and design since the beginnings of recorded his- 

 tory. I see it evidenced by the thousands of films exposed by a part of 

 the million or more people who visit the New York Botanical Garden 



