4 o8 POPULAR SCIENCE MONTHLY. 



enzymes, invisible organisms. Is it coincidence of fate that with the 

 growing importance of the problem of the invisible organism there 

 comes the invention of a microscope of surpassing excellence with 

 which the seeing of molecules is a hoped for possibility ? 



The science of plant pathology is indeed young. It has yielded 

 much, and it is still full of promise. In the achievement of the results 

 to come draught will be made upon the sister sciences even more than 

 in the past. Plant physiology waits upon chemistry; plant pathology 

 upon plant physiology, and chemistry in return receives valuable con- 

 tribution from both. Mathematics, physics and geology all contribute 

 to the general upbuilding. The sciences, though becoming more di- 

 vergent instead of becoming more independent, are yearly becoming 

 more dependent, each using the discoveries of the others to gain new 

 foothold or new tools in the search for truth. Often it is the frontier 

 territory lying between two sciences which, belonging distinctively to 

 neither, is least worked, and therefore presents most promising terri- 

 tory for conquest. Such is the history of the comparatively new sci- 

 ences of physical chemistry, physiological chemistry and biometrics. 



Nor does the field belong exclusively to either the devotee of pure 

 science, so-called, or of applied science. The study of problems seem- 

 ingly most remote from any practical ends has often proved funda- 

 mental in the upbuilding of vast industrial growth. Bacteriology was 

 born of crystallography. The father of galvanic electricity was derided 

 as the frog's dancing master. Nor does the avowed object in view 

 give a sure key to the ultimate outcome. Alchemy, though never 

 attaining the end sought, hastened immeasurably the era of industrial 

 chemistry. Nor may it be said that applied science is inferior, for 

 without the application the fundamental principles are of no avail in 

 the promotion of the welfare of man. 



Intensive laboratory study with no object other than the increase 

 of knowledge of molecular construction has led to the commercial 

 production of many important compounds. The present oat smut 

 treatment by formalin owes its practicability equally to pure science 

 in the chemical study that rendered the production of formalin prac- 

 ticable at moderate cost, and to pure science of the botanist who from 

 mere interest in fungous growth discovered the nature of parasitism, 

 and to the practical scientist who applied the knowledge of the chemist 

 and the botanist to the solution of a definite agricultural problem. 

 The distinction between pure science and applied science is invidious. 

 It is not a difference based upon the nature of the knowledge; rather 

 upon the motive of the worker. All true science is practical, either 

 remotely or directly, and the man of applied science is but completing 

 the work of the pure scientist. Especially does the future of plant 

 pathology rest with both. 



