DE. W. EOBEETS ON BIOGENESIS. 
465 
rature was equivalent to a shorter exposure to a higher temperature. For example, 
speaking roughly, an exposure for an hour to a heat of 100° Cent, was equivalent to an 
exposure for fifteen minutes to a heat of 109° Cent. 
3. Slightly alkaline liquids were always more difficult to sterilize than slightly acid 
liquids. This was probably due to the fact that albuminoid matter is more easily and 
more completely coagulated by a given heat in acid than in alkaline solutions. 
4. No organic liquid or mixture, subjected for however short a time to the heat of 
boiling water, ever produced (provided there was no fresh infection) any fungoid 
or torulaceous organisms*. If germination took place, the organisms produced invari- 
ably belonged to the great group of Bacteria. This appears to indicate that Torulce 
and their germs are more easily destroyed by heat than Bacteria and their germs. No 
development of Bacteria into fungoid vegetations was ever observed. 
5. Sterilization generally proved to be permanent if germination did not occur within 
four days. Sometimes, however, germination took place on the sixth or eighth day, 
and very rarely even as late as the tenth and twelfth day. Differences in the degree of 
warmth at which the preparations were maintained (after the heating) accounted for 
most of these cases of retarded germination, but not for all. Some I explained in this 
way : — the flasks were often moved about and disturbed, and possibly their contents 
were thus brought into contact with unsterilized portions which had spurted about the 
sides of the flask during ebullition. Neither of these explanations, however, appeared 
applicable to some of the cases of retarded germination. There was certainly no con- 
stant relation between retarded germination and the amount of heat used in the experi- 
ment. As a rule, germination, if it took place at all, was as prompt in preparations 
which had been boiled for an hour as in those which had only been boiled for five 
minutes. Something further will be said of these cases of retarded germination at the 
end of the third section. 
Section II.— ON THE CAPACITY OE THE JUICES AND TISSUES OE ANIMALS AND PLANTS 
TO GENEEATE BACTERIA AND TORULAE WITHOUT EXTEANEOUS INEECTION. 
It cannot be doubted that if the juices and tissues of healthy plants and animals 
could be placed, without extraneous contamination, in circumstances favourable to ger- 
mination, their behaviour under such circumstances would furnish important data in 
the controversy respecting the origin of Bacteria and Torulce. If, for example, it was 
found that the blood, flesh, milk, and urine of an animal, the contents of an egg, and 
the juices and tissues of a plant remained permanently barren, although adequately 
supplied with moisture, air, warmth, and light — so long as extraneous infection was 
prevented — such a result would furnish the strongest argument hitherto adduced in 
favour of the view that the appearance of Bacteria and Torulce in organic infusions was 
* Mention will be made subsequently of exceptions to this rule, or rather apparent exceptions, for they evi- 
dently belong to a totally different category. 
MDCCCLXXIV. 3 Q 
