ix.] BACILLUS. 107 



pole or at one of the long sides, and at this point a pale 

 projection appears. This projection increases in length 

 and gradually becomes as long as a bacillus, the investment 

 of the spore gradually fading away. This new bacillus soon 

 divides into two, and so on. 



The spores are capable of germinating independently of 

 the free access of air. 



It has been shown by Engelmann that the presence and 

 renewal of oxygen as well as a certain concentration of the 

 nutritive material is essential for the motility of those bacteria 

 that are possessed of cilia, i.e. that are possessed ot 

 locomotion. 



As long as the bacteria are living, their protoplasm does 

 not combine (stain) with nitrate of silver solution, only after 

 death does this become possible. Hereby an index is 

 furnished for ascertaining whether, and which, bacteria in a 

 given sample are living, and which are dead. There is no 

 difference in this respect, i.e. in respect of the different 

 reaction of nitrate of silver on living and dead protoplasm, 

 between the protoplasm of bacteria and that of other vegetable 

 or animal tissues. 



All bacteria, pathogenic and non-pathogenic, require for 

 their growth and multiplication oxygen, which they either 

 obtain from the medium in which they grow, and which 

 oxygen is dissolved in those media, or if this is consumed 

 or absent it is obtained by the bacteria in the process of the 

 chemical decomposition of the carbohydrates and proteids 

 present. Dr. Dupre 1 has shown that the presence or 

 disappearance of oxygen (air) dissolved in water is a precise 

 gauge, in the first case of the absence, in the second of the 

 growth, of microphytes. 



1 Report of the Medical Officer of the Local Government Board, 1884. 



