December 31, 1915] 



SCIENCE 



927 



tal disease and psycho-therapy, as well as 

 to educational theory and practise, that we 

 must look for new methods of discipline 

 and education in prisons, reformatories, 

 and houses of correction. Preventive 

 medicine and sanitary reform have shown 

 the right way of dealing with these chronic 

 sores in the body politic. 



The interrelations of the sciences are 

 vividly taught by the history of biology 

 during the past eighty years. Biological 

 science is deeply indebted to physical 

 science for the new instruments of pre- 

 cision which the biologist uses in determin- 

 ing and recording his facts. The tele- 

 phone, the x-ray, and all the electrical 

 apparatus for recording fluent observa- 

 tions and making certain note of very 

 minute portions of time and space have 

 been invaluable additions to the resources 

 of the biological investigator. Many of 

 the instruments which are indispensable 

 in botanical and zoological laboratories 

 were not invented for biological uses, but 

 for physical or chemical uses. The dental 

 practise called orthodontia has profited 

 greatly by the use of the x-rays, because 

 the Roentgenograph exhibits the precise 

 abnormalities in the jaws and the concealed 

 teeth which need to be remedied. The art 

 of photography has contributed much to 

 biological research and biological teaching, 

 although developed and improved more 

 for commercial and astronomical purposes 

 than for biological. The microscope itself 

 and the immersion lens, tools indispensable 

 in the study of microorganisms of all sorts, 

 were long used in pure botany and zoology, 

 before they became the necessary tools of 

 applied biological science. 



Again, the long series of successful ap- 

 plications of biological science illustrates 

 strikingly the impossibility of drawing 

 any fixed line of demarcation between pure 

 and applied science, or of establishing an 



invariable precedence for one over the 

 other. Sometimes an application is sud- 

 denly made of one fragment of an accu- 

 mulation of knowledge which pure scien- 

 tists have made without thought of any ap- 

 plication; and sometimes a bit of knowl- 

 edge successfully applied stimulates pure 

 scientists to enter and ransack the field 

 from which the bit came. The latter proc- 

 ess was strikingly illustrated when the 

 large group of the mosquitoes was studied 

 with ardor, because two species became 

 famous, one as the carrier of malaria, and 

 the other of yellow fever. The anatomy 

 and habits of the typhus fever louse had 

 been worked out many years before that 

 insect became known as a carrier of typhus 

 fever. Long before salvarsan was proved 

 valuable for killing the syphilis micro- 

 organism in the human body, a series of 

 organic compounds derived from benzol 

 and containing arsenic had been elaborately 

 studied, and the means of producing them 

 made known by chemists who had not the 

 faintest suspicion that a safe remedy for 

 the most destructive of contagious diseases 

 in the human species was later to be found 

 in a new member of the series having a 

 reduced arsenical potency. The pure 

 scientist often feels, and not infrequently 

 expresses, contempt for applications of 

 science and for the men that make them. 

 Sometimes the seeker for valuable appli- 

 cations of scientific knowledge feels no in- 

 terest whatever in researches of which no 

 industrial application seems feasible or 

 probable, and confesses publicly this lack 

 of interest. The facts seem to be that all 

 such feelings are narrow and irrational; 

 that no mortal can tell how soon a practical 

 application of a scientific truth, which 

 seems pure in the sense that it has no pres- 

 ent application, may be discovered; and 

 that, on the other hand, innumerable ap- 

 plications are nowadays made of truths 



