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THERMAL DEATH-POINTS 65 
e, There remains, therefore, an intermediate heat-zone 
_ - (ranging from a little below 140° to a little below 
158° F.), after an exposure to which the inoculated 
organic infusions are apt to become more slowly 
turbid, although inoculated saline solutions raised to 
the same temperature invariably remained unaltered.” 
The cause of this difference was later on dealt 
with in another communication to the Royal Society. 
It is unnecessary, however, to go into this question 
now, since it is at present generally admitted by 
bacteriologists that Bacteria and Torule in their 
active state, as they are found growing and multiply- 
ing in fluids, are invariably killed by a brief exposure 
to temperatures ranging between 140 and 158° F. 
(60°-70° C.)-—and for the most part nearer to the 
former than to the latter limit. 
Then, again, besides Bacteria and Torule, the 
bodies which are prone to show themselves at times 
in experimental vessels raised to much higher 
temperatures are ordinary Moulds. And in regard 
to such organisms Sachs says!: “ Of ninety-four ex- 
periments which were made by Tarnowski with all 
possible precautions, the result was that the spores of 
Penicillium glaucum and Rhizopus nigricans . . 
heated in their proper nutrient fluids nevertheless 
entirely lost their power of germination at 54° or 
55 GC. m3r F,).” 
So far then the various experimental results upon 
the question of “vital resistance” to heat have 
yielded remarkably harmonious results. There is 
still another side to the question, however, which 
1 “Text-book of Botany,” Transl. 1875, p. 651. 
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