DISCOVERY 



331 



tion there was life, and that the germs of this life were 

 borne on the dust of the air. This involved him in a 

 discussion which was to last for many a long year to 

 come. 



To convince the heterogenists, those who still 

 beheved in spontaneous generation, Pasteur set to 

 work to make numberless little glass bulbs with long- 

 drawn-out necks ; into these he introduced infusions 

 which would easily ferment ; he boiled them to ensure 

 sterility, and sealed them up while hot. On opening 

 his little bulbs in %'arious localities, the air rushed in 

 to fill the vacuum that had been formed ; the bulbs 

 were then sealed up again and set aside to ferment if 

 they would. His contention was that only those ' 

 which had been opened in a dust- cmd germ-laden 

 atmosphere would show signs of life. Not satisfied 

 with the purity of the air of his native Jura, to make 

 doubly sure he undertook a special journey to Chamonix 

 and opened some of his fiasks on the glacier. The 

 results of these experiments turned out exactly as he 

 had predicted they would, and he communicated them 

 to the Academy in March 1880 : " If all the results 

 that I have obtained until now are compared, it seems 

 to me that it can be affirmed that the particles of dust 

 suspended in the atmospheric air are the exclusive 

 origin, the necessary condition, of life in infusions." 



In the meantime he was pursuing his work on fermen- 

 tation, and had discovered why it was that wine some- 

 times turned sour. This was due, he said, to a micro- 

 scopic fungus {Micodcrma aceti), which carried the 

 oxygen of the air to the alcohol. He also showed that, 

 by merely warming the wine to quite a low tempera- 

 ture, this fermentation could be inhibited and the wine 

 kept in sound condition indefinitely. In Austria this 

 process was already known as pasteurisation as early as 

 1865. It is amusing to read of Pasteur, while on a visit 

 to Napoleon III and the Empress Eugenie, sneaking 

 off to the Imperial wine-cellar with the head butler to 

 see whether he could find any diseased bottles of 

 wine. 



In 1865 his work on fermentation was again inter- 

 rupted, and he was sent to Alais to investigate the 

 disease which was decimating the silkworms in this 

 district. Again he relied on his direct experimental 

 method and his microscope. He soon found the cause 

 of the trouble and suggested a means of overcoming it, 

 by examining the moths with the microscope after they 

 had laid their eggs, and rejecting the eggs of those 

 moths which showed the characteristic spots of the 

 disease. In this way the healthiness of next year's 

 worms was ensured. Some years later he had the 

 satisfaction of seeing a huge silkworm factory named 

 after him, with some si.xty to seventy women, armed 

 with microscopes, examining the moths. 



In the summer of 1871, while staying at Clermont 



Ferrand with an old pupil, Pasteur paid a visit to the 

 local brewery, and was astounded by the general state 

 of ignorance of their art displayed by the brewers. 

 He soon determined to make an exhaustive study of 

 the subject with a view to furthering the French 

 industry. To this end in the autumn he went off to 

 London to visit the great English breweries. After 

 the customary very careful microscopic examination 

 of all the yeasts used to prepare the various kinds of 

 beer, he was able to formulate the following maxim : 

 " Every marked alteration in the quality of the beer 

 coincides \vith the development of micro-organisms 

 foreign to the nature of true beer yeast." 



Hitherto Pasteur's discoveries had not led him into 

 the field of medicine, though it was obvious that sooner 

 of later he must attack the problem of the origin of 

 disease. To understand fully what Pasteur did for 

 humanity, one must clearly realise, firstly, that medicine 

 was at this time little short of what would now be 

 regarded as quackery, and, secondly, that the scientist 

 was looked upwn almost with contempt by the medical 

 profession. The acknowledgment by Lord Lister of 

 his indebtedness to Pasteur was in itself no mean 

 triumph for this humble seeker after truth. 



The ravages of anthrax among the herds of France 

 gave Pasteur his opportunity. Though he was not 

 actually the discoverer of the anthrax bacillus, he did 

 more to elucidate the mysteries of this disease than any- 

 one else. Again attacking the problem with his two 

 weapons, experiment and the microscope, he showed in 

 the first place how pure cultures might be made in a 

 sterile broth ; secondly how essential it was to take the 

 infected blood from an animal recently dead of the 

 disease for this purpose, for, if not, the bacillus of 

 septicaemia would also be present to complicate 

 matters. He even succeeded in separating the two, 

 showing how one was aerobic and the other anaerobic 

 (capable of living without air). Having obtained the 

 pure culture, he showed that, if it were injected into a 

 healthy animal, all the symptoms of the disease would 

 be reproduced and eventually the animal would die. 

 If, however, the culture was kept at a temperature of 

 about 42° C. for several days it lost its virulence, and 

 when injected into the healthy animal it now only gave 

 rise to a benignant malady which had the property of 

 preserving it from the virulent form. Thus was the 

 anthrax vaccine discovered. Long years of study and 

 hundreds of experiments were needed to arrive at these 

 results, and even then many more years were spent in 

 convincing the veterinary surgeons of the truth. A great 

 public demonstration on a large number of sheep with 

 proper controls was not even enough to convince the 

 most sceptical. 



In the meantime Pasteur had been making a study 

 of cliicken-cholera, and had isolated its bacillus, pre- 



