136 The Department of Plant Physiology [334 



are classified and identified are physiological, since the 

 processes induced by these minute organisms happen to be 

 more easily observed than are their structural differences. 



Application of Physiological Science Just as physics, 

 chemistry, climatology and biological morphology become 

 applied in physiology, so does physiology become applied in 

 many other lines of human activity. As with other sciences, 

 there are, in general, two groups of applications that are pos- 

 sible. First, there is the general application of physiologi- 

 cal knowledge and principle to the formation of what has 

 been called a "philosophy of the universe." This is perhaps 

 its application as "pure science/ 5 and for this application 

 plant physiology is almost, if not quite, as valuable as is 

 animal physiology. Such application is not usually called 

 an application at all, not being primarily practical for the 

 physical aspects of human life, in the sense of "buttering 

 bread." But there are still men who do not live by bread 

 alone, and a commercial age has not yet proved that a gen- 

 eral appreciation of the relations of the things about us may 

 not be ultimately as valuable to the human world as are 

 those things which money buys directly. It is in this direc- 

 tion of application that modern natural science claims at 

 least an equality with philology, history and the other 

 humanities. 



The second group of applications possible for physiologi- 

 cal science includes those commonly called practical, by which 

 food and clothing and dwellings may become more readily 

 available to human beings, and by which human health and 

 comfort may be enhanced. Just as animal physiology finds its 

 most numerous applications of this sort in the fields of medi- 

 cine, surgery, hygiene, animal husbandry, etc., so plant physi- 

 ology contributes most to human physical welfare in the 

 fields of agriculture, forestry, fermentation operations, bac- 

 teriology, etc. These applications are more interesting to 

 more persons than are those of the first group and their 

 importance is not to be minimized. Indeed, the more a sci- 

 ence may be practically applicable the more opportunity it 

 may have for becoming philosophically applicable. The two 



