150 



Dr. H. C. Bastian on the [June 15_, 



different observers have demoustrated the correctness of this inference. 

 Boiled acid infusions guarded from contamination mostly remain pure 

 and barren if kept at temperatures below 77° ^. (25° C), though other 

 infusions similarly treated and similar in themselves, except that they 

 have been rendered neutral by an alkali, will oftentimes become corrupt 

 and swarm with organisms. The latter result follows still more fre- 

 quently with neutral infusions when they are exposed to a higher 

 generating temperature in the warm-air chamber ; and under this 

 stronger stimulus a small number of boiled acid fluids will also ferment. 



On the other hand, the influence of oxygen in promoting fermentation 

 has been fully appreciated since the early part of the present century. 

 Formerly an influence was assigned to it as an initiator of fermentation 

 as all-important as some chemists assign to living germs at the present 

 day. But this was a very exaggerated view. In some fluids, as the 

 author has shown, fermentation may be initiated just as freely, or even 

 rather more so, in closed vessels from which the air has been expelled 

 by boiling, as in others in which atmospheric air, and consequently oxy- 

 gen, is present. The explanation of this fact is probably to be found in 

 the supposition that, in starting the fermentation of these fluids, diminu- 

 tion of pressure may be of as much, or even of more, importance than 

 contact with free oxygen. In respect to other organic fluids, however, 

 the influence of ox3^gen seems decidedly more potent as a co-initiater of 

 fermentation than that diminution of pressure which is brought about 

 by hermetically sealing the vessel before the fluid within has ceased to 

 boil. Urine will be found to be an example of this latter class of fluids. 



The physical influence which has been employed in unusual intensity 

 in the present researches is lieat. 



Previous experimenters have never designedly had recourse to a gene- 

 rating or developing temperature above 100° E. (38° C). The heat em- 

 ployed has frequently been below 77° T. (25° C), though a temperature 

 between this and 95° E. (35° C.) has been regarded both by chemists and 

 biologists as most favourable to the occurrence and progress of fermenta- 

 tive changes generally. 



Early in the month of August 1875 the author ascertained the fact 

 that some boiled fluids which remained barren when kept at a tempe- 

 rature of 77°-86° F. (25°-30° C.) would rapidly become turbid and 

 swarm with organisms if maintained at a temperature of 115° E. 

 (46° C). More recently he has discovered the surprising fact that a 

 generating temperature as high as 122° E. (50° C.) may be had recourse 

 to with advantage in dealing with some fermentable solutions. Eluids 

 which would otherwise have remained barren and free from all signs of 

 fermentation have under the influence of this high temperature rapidly 

 become turbid and corrupt. This discovery is regarded as of great im- 

 portance in reference to the questions now under discussion, and it is 

 one which was quite unexpected. The author had previously shared in 



