176 
is to say, at a temperature of 120°6° C. To the fluids so 
treated no air was allowed access, except what had passed 
through the capillary bores of white-hot iron tubes. And yet, 
when the flasks were broken, after a certain time, organisms 
were found in the fluids which had been submitted to these 
conditions. Prof. Mantegazza has obtained organisms from 
the fluids of hermetically closed flasks, after these, containing 
the putrescible fluids and common air at ordinary atmospheric 
pressure, had been subjected for some time to a temperature 
of 140° C.; and Prof. Cantoni, of Pavia, has obtained bacteria 
and vibrios in the fluids of similarly prepared closed flasks, 
after these had been exposed in a Papin’s digester to a tempera- 
ture of 142°C. for four hours. And still, though no positive 
evidence has been forthcoming to show that the standard of vital 
resistance can be raised—though nobody has shown that any 
Living thing which has been made the subject of experimentation 
has been found alive after an exposure for a minute or two in 
a fluid raised to 109° C., or after an exposure for thirty minutes 
to a temperature of 130° C. in dry air or 7 vacwo, many scien- 
tific menare as much disinclined as ever to admit that the or- 
ganisms found by the above-mentioned observers could have 
been evolved de nave. : 
For all those, however, who form their opinions on such 
matters in accordance with scientific evidence, rather than in 
obedience to theoretical preconceptions, it must be admitted 
that the balance of evidence is at present altogether in favour 
of the supposition that organisms can arise de zov0. And it 
only remains for those who are opposed to.the notion from an 
a priori point of view to bring forward positive evidence tending 
to show that the standard of vital resistance, for the organisms 
in question, is much higher than it has been hitherto shown 
to be. 
Some of the additional evidence I have now to bring forward, 
therefore, only tends to strengthen the validity of the conclusion 
which was already deducible from the experiments of Pouchet, 
Wymann, Mantegazza, Cantoni, and others. ; 
Hitherto, in sperking of the experiments of Schwann, I have 
only incidentally referred to the destructive influence of heat upon 
the organic matter contained in the solutions, though very strong 
evidence could be adduced to show that such organic matter is 
notably altered after thee solutions have been raised to the 
temperature of 109°C. The disruptive agency of heat is fairly 
enough supposed by the evolutionists to destroy some of the more 
mobile combinations in each solution—to break up, more or less 
completely, in fact, those very complex organic products, whose 
molecular instability is looked upon as one of the conditions essen- 
tial to the evolutional changes which are supposed to take place. 
I shall postpone for the present the consideration of the question 
as to how far this destructive agency of heat is affected by the alka- 
linity, neutrality, or acidity of the fluids, though T shall towards 
the close of this paper bring forward evidence tending to show 
that organic matter in acid solutions is more damaged by the 
temperature of 100° C. than is that which is contained in neutral 
or slightly akaline solutions, when these are heated to the same 
extent. 
To any one looking boldly at the problem, the question which 
now seems to suggest itself is, whether any other substances can 
b2 employed in place of the organic matter, suc as would not 
b> injured by a temperature of 100° C., and which, whilst con- 
taining the necessary elements for the formation of an or- 
ganism, might also permit the occurrence of those peculiar 
molecular re-arrangements which result in the formation of 
Living things? Postponing, however, the consideration of this 
question for the present, I will first refer to the influence of 
another of the detrimental conditions involved in Schwann’s 
experiments. 
In those instances where the results were positive, and in 
which calcined air and previously heated organic solutions were 
shut up in hermetically-sealed vessels, nothing but the lowest 
forms of living things ever appeared—mere monads, bacteria, 
and vibrios—and these generally not till after the expiration of 
two, three, or more months. Thereseems reason to believe that 
the delay, and the very low forms of the organisms met with, 
are attributable, in great part, to the increased tension which 
almost invariably occurs within the closed vessels. In some 
cases the tension becomes so great that it ultimately bursts the 
flasks. This tock place several times in the course of Dr. Child’s 
experiments. After reflection upon these facts, it seemed to 
me that there was not much room for surprise, looking at it from 
the evolutionist’s point of view, that the results should have 
NATURE 
[ Fuxe 30, 1870 
been so unsatisfactory. The small amount of space above 
the level of the fluid, is already occupied, at the time that 
the flask is hermetically sealed, with air under ordinary 
atmospheric pressure. But, when putrefactive or evolutional 
changes begin to take placein the fluids containing organic 
matter, such changes are almost sure to be attended by the 
liberation of gases either simple or compound. And in direct 
proportion to the extent of the liberation, so does the tension and 
consequent pressure upon the fluid increase within the flask. This 
pressure upon the solutions might and probably would tend to pre- 
vent, in proportion to its extent, those life-giving re-arrangements 
which are presumed to take place amongst the molecules of the 
organic matter contained therein, Having come to this con- 
clusion, and as there also seemed to be good reason for the 
belief that atmospheric air was not needed for the development 
of bacteria and vibrios, it occurred to me that it would be possible 
so to modify the experiment of Schwann that it might be repeated 
under conditions more satisfactory to the evolutionists, and at the 
same time in a way which would be hot less in accordance with 
the views of the panspermatists. The withdrawal ofall air from 
the flasks in which the boiled solutions were contained, rather 
than the admission of calcined air, seemed to be the kind of 
modification which was desirable.* Then the contamination 
of the boiled fluids with possible atmospheric germs would be as 
effectually provided against as if air had been only allowed to 
enter after it had been calcined, and the seemingly obvious ad- 
vantage would be attained that there would be even greater 
freedom than usual for the commencement of evolutional changes, 
on account of the diminished pressure upon the fluids contained 
im vacuo, It was presumed, also, that changes might go on fora 
certain extent before the evolution of gaseshad been sufficient 
to exercise such a repressive influence as to prevent their con- 
tinuance. 
The results of experiments conducted upon these principles 
have been most uniform, and have been of such a nature as 
to tend to support the truth of the reasonings which dictated 
them. 
The flasks employed have generally been of small size, capable 
of holding about two ounces of fluid. These have proved to be 
quite large enough, and their small size made it easy for me 
to manage the whole process with a very slight amount of assis- 
tance. The method adopted was as follows :—After each flask 
had been thoroughly cleaned with boiling water, three-fourths 
of it was filled with the fluid which was to be made the subject 
of experiment. With the aid ofa small hand blow-pipe and the 
spirit-lamp flame, the neck of the flask, about three inches from 
its bulb, was then drawn out till it was less than a line in 
diameter. Having been cut across in this situation, the fluid 
within the flask was boiled continuously for a period of from ten 
to twenty minutes. At first ebullition was allowed to take place 
rapidly (till some of the fluid itself frothed over) so as to procure 
the more thorough expulsion of the air; then the boiling was 
maintained for a time at medium violence over the flame of 
my reading-lamp, whilst the greatly attenuated neck of the flask 
was heated in the flame of a spirit-lamp placed at a correspond- 
ing level. The steam for a time poured out violently into the 
flame of the spirit-lamp ; and whilst my assistant (my wife) turned 
down the flame of the reading-lamp so as to diminish still further 
the violence of the ebullition, I directed the blow-pipe flame 
upon the narrow orifice of the neck of the flask. and so sealed 
it hermetically. Immediately that the orifice was closed, the 
heat was withdrawn from the body of the flask. 
After a little practice I soon became able to procure in this 
way an almost perfect vacuum. Even though the vessels were 
* I was actually led to adopt this important modification, perhaps, by 
a merce chance. In the spring of last year Mr. Temple Orme, of Uni- 
versity College, had kindly undertaken to perform some experiments with 
me bearing upon the subject of ‘‘ Spontaneous Generation.” We at first 
proposed to repeat, with some very desirable variations which he suggested, 
Schultze’s experiments. One day, however, he told me he had boiled an infusion 
of hay for four hours, and had then hermetically sealed the neck of the flask 
whilst ebullition continued. In this way a more or less perfect vacuum was 
procured. This he did as a sort of tentative experiment, and it was then, on 
thinking over the subject, that I resolved to give the plan a thorough 
trial, as it appeared to me that by so doing I Shout be working under con- 
ditions which were most in accordance with the theory of evolution. I per- 
formed four experiments at that time in concert with Mr. Temple Orme, 
with hay infusions which had been boiled fer four hours and had then been 
sealed up 7” wrcvo. In each of these fluids organisms were found after a com- 
paratively short time. These were the first experiments performed under 
such conditions. In my subsequent work I have not had the benefit of Mr. 
Orme's personal assistance, although I have frequently profited by sugges- 
tions which he has made. 
