Decembek 26, 1902.] 



SCIENCE. 



100.'). 



Ocei;rring the world over, constantly with 

 ns, invading all homes, and keeping the 

 death rate in cities perpetually high, at 

 times they have swept, with the fury of 

 a fiery volcanic blast, over large regions 

 of the earth's surface, sparing few, and 

 leaving in their train empty hoixseholds 

 and cities of death. Recent statistics have 

 claimed that one of these diseases, tuber- 

 culosis, alone kills one seventh of all the 

 population of the world. 



To what are these pestilential visita- 

 tions due 1 Many have said, ' To the anger 

 of offended gods ' ; others, ' To the displeas- 

 ure of a divine Providence ' ; the early 

 physicians, 'To a wrong admixture of the 

 humors'; the later pathologists, 'To mys- 

 terious fermentations.' But none of these 

 answers has touched the vital point. This 

 was reserved for a simple, modest and 

 earnest student of science, of hiimble origin, 

 the son of a, French tanner, a man un- 

 hampered by medical tradition, seeking 

 only the truth, and possessed of no genius 

 except the genius of perseverance. To 

 Louis Pasteur, more than to all others, 

 should be given the honor of having solved 

 the problem of the causation of the?e dread 

 diseases. He laid the foundations of the 

 new science, broad and deep, with surpris- 

 ingly few errors of judgment. 



It is instructive to look at the leading 

 features' of Pasteur's life-work. From the 

 beginning of his career, Pasteur was the 

 defender of pure science, yet his work 

 demonstrates well the ultimate practical' 

 value of what seems at first purely scien- 

 tific. At the age of thirty-one he became 

 a professor and dean of the Faculty of 

 Sciences at Lille, and in his opening address 

 he said to his students: 'Tou are not to 

 share the opinions of those narrow minds 

 who disdain everything in science that has 

 not an immediate application.' And then 

 he ciuoted that charming story of Benjamin 



Franklin, who when witnessing a demon- 

 stration of a scientific discovery, was asked :: 

 'But what is the use of it?' Franklin re- 

 plied: 'What is the use of a new-born 

 child 1. ' 



Pasteur's various scientific labors form 

 a strikingly connected series, each being 

 logically bound to those that preceded it. 

 Beginning with a study of the forms and 

 significance of the crystals of certain salts, 

 in which he made use of fermentation 

 processes, he passed directly to the study 

 of fermentation itself. He early appre- 

 ciated the fact that this phenomenon, due 

 as it is to the presence in fermentable 

 liciuids of microscopic living bodies, bears; 

 significantly on fundamental physiological 

 processes; and his labors directly estab- 

 lished the germ theory of fermentation. 

 Fermentation led to his famous investiga- 

 tion of the problem of spontaneous genera- 

 tion, which for ages had vexed the scientific 

 and popular mind. Organic liquids ex- 

 posed to air soon become putrid and filled 

 with microscopic beings, the origin of 

 which was a mystery. Many believed them 

 to originate spontaneously; others thought 

 that the air contained a mysterious creative 

 influence. ' If in the air, ' thought Pasteur, 

 'let us find it'; and by the simple device 

 of stopping the mouths of flasks of steril- 

 ized liquids by a bit of cotton-wool, he was 

 able to filter out the influence and keep his 

 liquids pure and free from life. At the 

 end of a year's active work he announced 

 a most important fact: 'Gases, fluids, 

 electricity, magnetism, ozone, things known 

 or things occult, there is nothing in the air 

 that is conditional to life except the germs 

 that it carries.' His position was assailed 

 by clever men, and he was forced to de- 

 fend himself. It was here that his power 

 of perseverance first formidably asserted 

 itself. The struggle lasted for years, and 

 Pasteur repelled each attack, point by 



