454 Br. Allan Macfadyen [June 8, 



protoplasm becomes inert or dies. The best growths were always 

 obtained at 55-65° C. Their wide distribution was of a striking 

 nature. They were found by us in river water and mud, in sewage, 

 and also in a sample of sea water. They were present in the 

 digestive tract of man and animals and in the surface and deep layers 

 of the soil as well as in straw and in all samples of ensilage examined. 

 Their rapid growth at high temperatures was remarkable, the whole 

 surface of the culture medium being frequently overrun in from fifteen 

 to seventeen hours. The organisms examined by us (fourteen forms 

 in all) belonged to the group of the Bacilli. Some were motile, 

 some curdled milk, and some liquefied gelatin in virtue of a 

 proteolytic enzyme. The majority possessed reducing powers upon 

 nitrates and decomposed proteid matter. In some instances cane 

 sugar was inverted and starch was diastased. These facts well 

 illustrate the full vitality of the organisms at these high tempera- 

 tures, whilst all the organisms isolated grew best at 55°-65° C. A 

 good growth in a few cases occurred at 72° C. Evidence of growth 

 was obtained even at 74° C. They exhibited a remarkable and unique 

 range of temperature, extending as far as 30° of the Centigrade 

 scale. 



As a concluding instance of the activity of these organisms we 

 may cite their action upon cellulose. Cellulose is a substance that 

 is exceedingly difficult to decompose, and is therefore used in the 

 laboratory for filtering purposes in the form of Swedish filter paper, 

 on account of its resistance to the action of solvents. We allowed 

 these organisms to act on cellulose at 60° C. The result was that in 

 ten to fourteen days a complete disintegration of the cellulose had 

 taken place, probably into C0 2 and marsh gas. The exact conditions 

 that may favour their growth, even if it be slow at subthermophilic 

 temperatures, are not yet known — they may possibly be of a chemical 

 nature. 



Organisms may be gradually acclimatised to temperatures that 

 prove unsuited to them under ordinary conditions. Thus the anthrax 

 bacillus with an optimum temperature for its development of 37° C, 

 may be made to grow at 12° C, and at 42° C. Such anthrax 

 bacilli proved pathogenic for the frog with a temperature of 12° C, 

 and for the pigeon with a temperature of 42° C. 



Let us in a very few words consider the inimical action of tem- 

 perature on bacterial life. An organism placed below its minimum 

 temperature ceases to develop, and if grown above its optimum 

 temperature becomes attenuated as regards its virulence, etc., and 

 may eventually die. The boiling point is fatal for non-sporing 

 organisms in a few minutes. The exact thermal death-point varies 

 according to the optimum and maximum temperature for the growth 

 of the organism in question. Thus for water bacteria with a low 

 optimum temperature, blood heat may be fatal ; for pathogenic bacteria 

 developing best at blood heat, a thermophilic temperature may be 

 fatal (60° C.) ; and for thermophilic bacilli any temperature above 



