
THERMAL DEATH-POINTS 69 
the laboratory, would not often have found the 
higher temperatures with which experiments were 
there made. And, as the authors say, it is only 
“reasonable to suppose that such a widely dis- 
tributed group of organisms must find favouring 
natural conditions outside the factor of temperature, 
these conditions being probably of a chemical 
nature.” 
Although some of these thermophilic Bacteria are 
undoubtedly capable of flourishing at temperatures 
that prove rapidly fatal to other Bacteria, they are 
not so remarkable in this respect as the Conferve 
referred to in the last chapter, many of which 
flourished at even higher temperatures. We have 
still much to learn concerning each of these groups of 
organisms of lowest grade ; but as we are distinctly 
told by Macfadyen and Blaxall that the thermophilic 
Bacteria were never detected in tap water (and as 
they would be still less likely to be found in dis- 
tilled water with which the most important experi- 
ments to be recorded in this work have been made), 
they may, from our point of view, be almost as much 
disregarded as the Conferve of the hot springs. 
Neither of these exceptional organisms are, in fact, 
at all likely to complicate our work. 
Seeing that in the experiments with saline and 
organic infusions recorded in the last chapter the 
solutions were inoculated with a drop of a fluid in 
which either Bacteria alone, or Bacteria and Torule, 
were multiplying rapidly, we must suppose that they 
were multiplying in their accustomed manner, as 
