The Scottish Naturalist. 75 



any ideas but those of disease and death ? and how great a place 

 do the bacteria fill in the minds and in the investigations of 

 modern physicians, especially of those concerned in tracing the 

 nature of epidemic diseases, their origin, and the methods of their 

 diffusion ? Already it is widely admitted that bacterial origin is 

 proved in anthrax or splenic fever, in consumption or tuberculosis, 

 and in various other diseases ; and the same is asserted in 

 regard to smallpox, typhoid fever, recurrent and malarial fevers, 

 cholera, pneumonia, and several other diseases of a virulent type. 

 In regard to wounds, the antiseptic treatment, now so generally 

 adopted by surgeons, in most cases with good results, is based up- 

 on the belief that the evil effects, formerly so frequent after opera- 

 tions, resulted from the introduction of bacteria from the surround- 

 ing atmosphere into the wounds. v The aim of antiseptic treatment 

 is to prevent the entrance of such living organisms ; and, since the 

 introduction of this method of treatment, operations are now 

 frequently undertaken with success that were formerly considered 

 unjustifiable. 



The importance of a knowledge of the bacteria in their relations 

 to disease explains the interest taken in them, and the number of 

 books on them that appear in constant succession, Their exces- 

 sive minuteness, and their modes of life, call for very careful in- 

 vestigations ; and every new discovery is hailed eagerly by many 

 whose interest in them is by no means purely scientific. 



The dread evoked by the disease-producing bacteria must not 

 be allowed to make us forget that many others are of infinite value 

 to mankind, since they are the active agents in effecting decom- 

 position of the dead bodies of animals and of plants, and in there- 

 by reducing them to conditions suitable for the nourishment of 

 larger plants. But for the bacteria dead bodies of all kinds would 

 remain dried up, but otherwise unchanged, to all time ; and much 

 of the most fertilising constituents in them could not be returned 

 to the soil, but must remain unavailable for the growth of new or- 

 ganisms. Analogous to this process of causing putrefaction is the 

 power that certain bacteria possess of giving rise to modes of fer- 

 mentation, while others give rise to the formation of saltpetre, where 

 rotting animal matter is in contact with potassic carbonate. There 

 seems good evidence to warrant the belief that various diseases in 

 domestic animals, as well as in mankind, e.g., glanders in horses, 

 are due to peculiar bacteria ; and the same holds good with certain 



