THE president's ADDRESS. 459 



work of fermentation or the manufacture of ginger-beer proceeds 

 uninterruptedly. 



The exact position of the Bacteria, or Schizomycetes, is as yet 

 a matter of speculation, being considered by some as nearest to 

 the fungi, and by others as presenting affinities with the Algae. 

 The fact is, some of the organisms included in the Schizomycetes 

 are algal-like and others fungal-like. 



All agree in the extreme simplicity of their morphological 

 characters : the marked changes in form and habit depending on 

 environment and other factors ; and on their exceedingly minute 

 size, even compared with the yeasts. 



Reproduction takes place by fission, or the separation into two 

 equal portions of an individual, each half, on assuming the size 

 of its parent, undergoing a similar di\^sion. A second mode of 

 reproduction is by the production of endospores within the cell 

 or body of an individual. 



Under favourable conditions, reproduction by fission, the most 

 usual method, takes place in a very short time. In the cholera 

 comma-bacillus twenty minutes is occupied in this process, hence 

 in a single day a progeny of sixteen hundred trillions would 

 result. This quantity of bacteria w^ould contain about one 

 hundred tons of solid residue. 



Some bacteria are characterised by the production of brilliant 

 colours, forming patches of blood-red, pink, green, yellow, etc., 

 on cooked meat, cheese, bread, and other organic substances. 

 Others again are strongly fluorescent. 



Smells agreeable or otherwise often result from the activity 

 of these organisms in promoting the decomposition or putre- 

 faction of organic matter, but, as already stated, a characteristic 

 feature of the group is the liberation of free nitrogen or 

 ammonia. 



Bacteria, like yeasts, are either aerobic or anaerobic, and in 

 addition respond to the stimulus of certain substances in solution, 

 which do not necessarily serve as food. The influence thus 



