1 20 [Proc. B. N. F. C, 



dall's Alpine investigations, he found that the higher we go 

 above the level of the sea, or the further from busy towns and 

 crowded streets, the more free from these microbes do we find 

 the air. Thus, at St. Paul's Cathedral, the Golden Gallery 

 yielded 11, the Stone Gallery 34., and the churchyard 70. 

 Some fifty years ago, Schwann demonstrated that fermentation 

 and putrefaction were due to micro-organisms. Henle argued 

 that contagious diseases had a similar origin. The real pro- 

 gress in this study dates from i860, when Pasteur, having 

 established Schwann's theory of fermentation, took up that of 

 Henle regarding living contagia. The researches of Pasteur, 

 Koch, Klebs, and others, have been the means of determining 

 the special cause of many diseases both in plants and animals. 

 Thus, Bacillus tuberculosis is found in the breath and tissues 

 of those afflicted with consumption ; Bacillus subtilis in 

 splenic fever, which is so fatal to cattle, and which is also com- 

 municable to man, in whom it is known as the wool-sorter's 

 disease, while Koch has discovered the Comma bacillus in 

 cholera ; and in typhoid fever, scarlatina, erysipelas, and other 

 diseases, special bacilli have been found. The general current 

 of recent investigations would seem to prove that micro- 

 organisms are widely diffused, that when they meet with a 

 suitable soil they develop and multiply, and that the diseases 

 are not so much due to the organisms themselves as to the 

 effect of certain poisonous chemical compounds which are 

 formed during the life of the organism, for the diseases can be 

 communicated by these poisons in entire absence of the germs. 

 Sir Henry Roscoe expresses the opinion that it is by chemical 

 rather than by biological investigation that the cause of diseases 

 will be discovered, and the power of removing them obtained. 

 The main feature of Pasteur's researches has been in the deve- 

 lopment, exterior to the body, of these organisms. It has been 

 found that in the case of Bacillus subtilis so developed, if kept 

 at a heightened temperature, it loses its virulence, and becomes 

 incapable of producing the poisonous compound. Animals 

 inoculated with it in this form sustain no mischievous results, 



