THERMAL DEATH-POINT OF LIVING MATTER. 187 



Insects and of Batrachia, agrees almost exactly with that which I 

 have established for Bacteria-germs, although at the time my own 

 experiments were made I was unaware of these particular results 

 obtained by Spallanzani. 



Is there, then, any thing in this fact concerning Bacteria and their 

 germs at all at variance with what we might have been led to expect 

 from our knowledge about the capacity for resisting heat shown by 

 other kinds of living matter ? Here, again, a negative answer may be 

 unreservedly given. The grounds for this opinion must, however, be set 

 forth, and, in dealing with this important question, I will range what I 

 have to say under the following heads : 1. The results obtained by 

 many other investigators, working quite independently of one another, 

 (and in many cases also without distinct reference to the Origin-of- 

 Life question), all go to show that different kinds of living matter are 

 killed when in the moist state at or below the temperature of 140 

 Fahr. 2. The only known exceptions to this rule are cases of a 

 special kind differing altogether from those with which we are at 

 present concerned. 3. Our knowledge concerning the thermal death- 

 point of Living Organisms and of Living Matter is remarkably har- 

 monious, and is in accordance therefore with what we know con- 

 cerning the unity of living matter generally. 4. The assumptions 

 entertained by some, in support of their notion that living matter un- 

 accustomed to the influence of heat is able to resist the destructive 

 action of boiling water, are of the most frivolous nature alike unsup- 

 ported by experiment and contradicted by all ordinary experience. 



1. Liebig proved that sugar-yeast [Torxda cerevisiw) entirely lost 

 its power of growth and germination at 140 Fahr. It has been ascer- 

 tained by Tarnowski, after numerous experiments conducted, as Sachs 

 says, 1 " with all possible precautions," that spores of Penicillium and 

 other common fungi, also most closely related by nature to Bacteria, 

 " entirely lost their power of germinating when heated in their own 

 nourishing fluids" to a temperature of 131 Fahr. Again, it has been 

 ascertained by Dr. Timothy Lewis 2 that the germs of tape-worms are 

 invariably killed at the temperature of 131, while Prof. Mantegazza 

 has shown that the male reproductive particles of frogs are killed by 

 exposure to the same heat. So far, therefore, concerning germs, in 

 addition to what I have already mentioned about Spallanzani's obser- 

 vations upon the eggs of Insects and Batrachia. Turning now to adult 

 organisms of different kinds or to their elemental parts, the following 

 facts maybe cited: Pouchet 3 found that all kinds of Ciliated Infu- 

 soria were certainly killed at 131 Fahr., and while confirming this 

 observation the writer found that a brief exposure to this temperature 



1 " Lehrbuch der Botanik," third edition, p. 626. 



2 " Eighth Annual Report of the Sanitary Commissioners with the Government of In- 

 dia," 1871, p. 139. 



3 " Nouvelles Experiences," etc., 1864, p. 38. 



