Page:Popular Science Monthly Volume 6.djvu/199

Rh 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 harmonious, and is in accordance therefore with what we know concerning the unity of living matter generally. 4. The assumptions entertained by some, in support of their notion that living matter unaccustomed to the influence of heat is able to resist the destructive action of boiling water, are of the most frivolous nature—alike unsupported by experiment and contradicted by all ordinary experience.

1. Liebig proved that sugar-yeast (Torula cerevisiæ) entirely lost its power of growth and germination at 140 Fahr. It has been ascertained by Tarnowski, after numerous experiments conducted, as Sachs says, "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 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 observations upon the eggs of Insects and Batrachia. Turning now to adult organisms of different kinds or to their elemental parts, the following facts may be cited: Pouchet found that all kinds of Ciliated Infusoria were certainly killed at 131° Fahr., and while confirming this observation the writer found that a brief exposure to this temperature