January 10, 1919] 



SCIENCE 



33 



and ask what my o\vti chosen field of chem- 

 istry, which for the lack of a better name we 

 still call pure chemistry, can contribute to the 

 cause of medicine. Let me say at once that I 

 speak almost on the defensive, I have been 

 asked so often by eminent physicians, by phys- 

 iologists and biologists of every kind, why 

 chemistry is so intolerably slow and backward 

 in solving what are quite obviously chemical 

 problems — problems striking at the very root 

 of our health and happiness. The answer 

 very simply is this : Pure chemistry aims to be 

 and is an exact science ; indefinite mixtures of 

 substances, such as our tissues and secretions 

 represent, interest us, it is true, most deeply, 

 but we can handle them altogether successfully 

 only to the extent that we can isolate from 

 them pure principles for exhaustive, complete 

 investigation, so complete tJiat we do not rest 

 imtil we have dissected the molecule of the 

 pure compound, have put it together again, 

 and thus have acquired first hand knowledge 

 of the exact function of each of its members. 

 In the same way, systems that contain more 

 variables than we can control rigorously, as 

 rigorously as the mathematicians, the phys- 

 icists and astronomers control their material, 

 pure chemistry puts aside imtil such a time 

 when our knowledge has advanced far enough 

 to give us exact knowledge of each component 

 in the system, to make possible a rigorous 

 analysis of the whole system. Every physician 

 knows what medicine would ho without dis- 

 section, without an exact knowledge of the 

 structure and location of the organs and mem- 

 bers of the body — every physician knows too 

 how the functioning of the parts in the whole 

 can be understood only by an accurate study 

 first of the functioning of each organ and each 

 member. Now, the scientific dissection and 

 reconstruction of the molecules of important 

 isolated principles is as a rule an extraordin- 

 arily difiicult problem. Thus it took Baeyer, 

 perhaps the greatest organic chemist of his 

 generation, some fourteen years to determine 

 what we call the structure of indigo, contain- 

 ing only some thirty atoms. But, his success 

 opened the way with the inevitableness of fate 

 to one of man's triumphs over nature: for 



with the knowledge of its structure, the key 

 was gained for the successful synthesis of 

 indigo and its artificial preparation on a large 

 scale, releasing many acres of land for the 

 growth of other important products for human 

 use. It took altogether some thirty-four years 

 to complete the campaign for the successful 

 production of indigo, and at that the campaign 

 was planned and conducted by sonie of the 

 keenest minds in our science and sustained by 

 the prosi)ects of rich rewards in gold for the 

 successful issue! Similar vital work was car- 

 ried out with other important dyes, such as 

 alizarin or turkey red, methylene blue, ma- 

 genta. I am emphasizing these facts, not only 

 to illustrate the method of pure chemistry, 

 but primarily to show what the successful 

 issue of its efforts means. These and other 

 dyes had been used commercially with an em- 

 pirical knowledge during the many years that 

 great investigators studied them from the 

 point of view of chemistry as an exact science 

 — but with the successful issue of their efforts 

 in the profound analysis of the molecular 

 structure of fundamental dyes, chemistry has 

 gained for man supreme and practically un- 

 limited power over the whole problem of color 1 

 It has made it possible for us to make at 

 will a dye of any properties we may desire — 

 fast dyes for any fabric, unstable, sensitive 

 dyes for photography, dyes of any conceivable 

 shade, fluorescing, if you please, with any de- 

 sired hue ! This instance of the power gained 

 by chemistry has already proved to be of great 

 value in medicine, by the development of 

 stains to differentiate cells, microorganisms, 

 tissues of every variety. 



The lesson of this conquest of the world of 

 color by man would be wholly lost, if you did 

 not carry from here the conviction that the 

 methods which have scored so brilliant a suc- 

 cess in one field are absolutely certain to be 

 equally successful in conquering the greater 

 world of bio-chemistry. The methods evi- 

 dently are painfully slow. It took two gen- 

 erations to complete the conquest of color — 

 would ten or twelve generations be too long 

 for the supreme conquest of the chemistry of 

 life? The campaign has already long been 



