MICRO-ORGANISMS IN RELATION TO MAN. 97 
vegetative cells are at once killed. On this observation was 
founded the intermittent system of sterilization, which consists 
in heating the liquid to be sterilized up to the boiling point 
ou several successive days, by which means the organisms 
developed from the spores during the preceding 24 hours are 
killed on each day, until finally no more spores remain to 
develop. 
The controversy over spontaneous generation, which had 
lasted for about one hundred and twenty-five years, was thus 
brought to a conclusion, and it is now an accepted fact that 
bacteria or microbes may be destroyed by heat and certain 
chemical reagents, and that once destroyed in any medium, 
the medium remains free from any putrefactive changes until 
fresh germs are introduced from without. The recognition of 
this fact led, amongst other things, to.the system of antiseptic 
surgery, with which the name of Lister will always be asso- 
ciated. 
Whilst the final engagements in the great war of abio. 
genesis were being fought, Pasteur, who may be regarded 
as the father of modern bacteriology, was busily engaged in 
studying certain diseases of wine. These he proved to be due 
to micro-organisms, and by adopting remedies based upon the 
facts I have mentioned, he put into the hands of wine-growers 
a means of preventing these diseases. Immediately following 
this, Pasteur was called upon to investigate a mysterious 
disease which was causing the greatest distress in the silk- 
growing districts of the Continent. The disease, which 
attacked the silk-worms and their eggs, spread with alarm- 
ing rapidity, until in one year in France alone, the loss is 
said to have been £4,000,000 sterling. For five years, from 
1865 to 1870, Pasteur investigated this epidemic, and success 
crowned his efforts; he proved that the tissues of the 
affected worms contained an organism, in the form of small, 
glistening oval corpuscles, which caused the disease. He was 
able to demonstrate their presence not only in the moths 
