The Various Ways in Which Plants Appeal 5 



boundary between useful and useless knowledge; they are one 

 and indivisible, and such boundary as may seem to exist is simply 

 a shadow that shifts over the surface, changing with times and 

 our customs. Accordingly, the only possible way in which human- 

 ity can obtain useful results from science, lies through the en- 

 couragement of the development of all of its phases; and this 

 may be done with the assurance that now and then some useful 

 applications will somewhere appear, and pay manyfold for it all. 

 And this is precisely the reason, moreover, why no good system of 

 education can confine itself to teaching useful knowledge alone. 

 It is unfortunately still true, as it was when Stephen Hales, the 

 founder of Plant Physiology, wrote nearly two centuries ago, that 

 pure science needs protection ''from the reproaches that the ig- 

 norant are apt unreasonably to cast on researches of this kind, 

 notwithstanding that they are the only solid and rational means 

 whereby we may ever hope to make any real advance in the 

 knowledge of Nature." When, therefore, the reader hears anyone 

 asldng what is the use of this or that phase of knowledge, or when 

 he sees practical men showing mipatience with the impractica- 

 bility of great scholars and contempt for the uselessness of their 

 knowledge, he may well state these facts by way of courteous 

 reproof. And he may even add, as to such knowledge, that 

 those w^ho pursue it, in the absence of the material rewards 

 reaped in full measure by practical men, deserve no less tribute 

 of respect and approbation than is accorded by common consent 

 to those whose efforts bring them personal wealth. Both in fact, 

 though in different ways, are contributing to the welfare and 

 progress of humanity. 



I have spoken, just now, of the pleasures of the study of Botany, 

 and over this theme I would hnger a little. It is true of all science 

 that the pleasures of its study lie deep, and one must reach far 

 before he can grasp them. It is not as with literature, for ex- 

 ample, which makes appeal to the feelings, that lie near the surface 

 and are easy to touch ; for science appeals chiefly to reason, which 



