Fuly 7, 1870| 
NATORE 
199 
positive results, and those of many other experimenters, may be 
considered to have a most important bearing upon the settle- 
ment of the general doctrine. It hecomes simply a question as 
to whether the conditions which were formerly believed suff- 
ciently stringent to destroy all pre-existing Living things within 
the experimental flasks are in reality adequate to effect this. 
Can the standard of vital resistance be raised? If the old land- 
marks cannot be shown to be false, then there is very far more 
evidence of all kinds in favour of, than there is against, the occur- 
rence of ‘spontaneous generation.” 
But in order, still further, to put this question beyond the 
region of doubt, I gladly availed myself of Prof. Frankland’s 
proffered aid. He very kindly offered to procure a perfect 
vacuum in my flasks, and then, after these had been herimeti- 
cally sealed, to expose them and the fluids which they contained 
for some time to a temperature of about 150° C. This temperature 
for a fluid is so very far in advance of that which is at present 
believed to be destructive to all the lower organisms, that it is 
perfectly fair for us to presume, till evidence be adduced to the 
contrary, that Living things would be completely destroyed by 
an exposure to such a temperature even for a single minute. 
It seemed desirable to try different kinds of solutions in this 
way, and I therefore asked Dr. Frankland to be kind enough to 
submit four flasks and their contents to this most stringent test. 
Tn order that they might be representative of the solutions with 
which I had already been working, one was to contain a freshly 
prepared and filtered infusion of turnip; another a solution of 
sugar, tartrate of ammonia, and phosphate of soda in distilled 
water ; another a solution of tartrate of ammonia and phosphate 
of soda alone in distilled water; whilst the last was to contain 
carbonate of ammonia and phosphate of soda in distilled water. 
The second of these solutions was submitted to these condi- 
tions by Dr. Frankland, on Feb. 11, 1870, together with two 
others, one containing turnip juice, and the other carbonate of 
ammonia and phosphate of soda. On the following day I re- 
ceived a letter from Dr. Frankland, in which he had written as 
follows :—‘‘ Yesterday, I exposed the three liquids to a tempera- 
ture of 150° C. for four hours. On taking them out of the 
digester this morning two were broken; one had probably 
burst with the pressure of carbonate of ammonia vapour, the 
other had received some slight shock which had broken off 
the extreme point of glass where it was drawn off before tlre 
blowpipe. The third, containing the tartrate of ammonia, 
sugar, and phosphate of soda, I send along with this, but fear 
you will not consider its contents favourable for your opera- 
tions, part of the sugar haying apparently been converted into 
caramel,” 
A few days afterwards (on Feb. 15) Dr. Frankland submitted 
the three other solutions to a similar treatment, and he has 
kindly furnished me with the following statement of the con- 
ditions to which they were subjected :— 
“*Fach liquid was placed in a glass tube about $inch in 
ciameter, 9 inches long, and closed at one end by fusion of 
the glass. The open end of the tube was then drawn out so 
as to form a thick capillary tube, which was afterwards con- 
nected with a Sprengel’s mercurial pump. The action of the 
pump soon produced a tolerably good vacuum, when on gently 
warming the liquid, the latter began to boil, its vapour ex- 
pelling the last traces ot air from the apparatus. After the 
boiling had been continued for several minutes, the tube was 
hermetically sealed at the capillary part. 
“‘Three tubes were prepared in this way, containing respec- 
tively— 
“1, Tumip juice ; 
**2. Solution of ammonic tartrate and sodic phosphate ; 
**3. Solution of ammonic carbonate and sodic phosphate. 
“The vacuum in tubes Nos. 1 and 2 was so perfect as to ren- 
der them good water-hammers. In the third tube the vacuum 
was not so good, owing, doubtless, to the evolution of car- 
bonic anhydride from the ammonic carbonate. 
“The three tubes were now placed in the wrought iron digester, 
described by me in the Philosophical Transactions for 1854, 
page 260. It consists essentially of a cylindrical iron vessel, 
with a tightly fitting cover, which can be securely screwed on 
to it. Through the centre of the cover passes an iron tube, 
which descends half way down the centre of the cylinder. 
This tube is closed at bottom, and contains a column of mer- 
eury about an inch long, and a thermometer plunged into the 
mercury shows the temperature of the licuid inside the digester. 
“Water being now poured into the digester until it covered the 
tubes, and the cover having been screwed on, heat was applied 
by means of a gas stove. 
“*The temperature was allowed to rise to about 150°C., and 
was maintained between 146° and 153°C. for four hours, and it 
is almost needless to say that every part of the sealed tubes and 
their contents was exposed to this temperature during the whole 
time. The glass tubes, though of moderately thick glass only, 
ran no risk of fracture, because the pressure inside them was 
approximately counter-balanced by the pressure of steam out- 
side. 
‘After cooling, the tubes wereremoved from the digester, when 
it was found that the turnip juice had become discoloured, and 
the liquid no longer acted as a water-hammer, showing that 
the vacuum in the tube had been impaired. The contents of the 
two remaining tubes were apparently unaltered, the vacuum in 
No 2. being as perfect as ever.” 
Experiment 17.—The tube containing the infusion of turnip 
was opened at the end of the twelfth day. 
When received from Dr. Frankland the fluid had been changed 
to a decided, but light brown colour, and there was some quantity 
of a blackish brown granular sediment at the bottom, though the 
solution was free from all deposit when placed in the digester. 
After this tube was suspended in the warm place, as the others 
had been, it remained in the same position till it was taken down 
to be opened. A slight scum or pellicle was observed on the 
surface —covering this partially—on the sixth day. During the 
succeeding days it did not increase much in extent, though it 
became somewhat thicker. Although very great care was taken, 
still the slight movement of the flask, occasioned in knocking 
oft its top, caused this pellicle to break up and sink to the 
bottom. * 
The contents of the flask emitted a somewhat fragrant odour 
of baked turnip, and the reaction of the fluid was still slightly 
acid. On microscopical examination, there was found very 
much mere granular dbyis of a brownish colour, which probably 
represented the brownish sediment seen when the tube was re- 
moved from the digester. There were, also, a very large number 
of dark apparently homogeneous reddish brown spherules, mostly 
varying in size from ys'55" to spipy" in diameter, partly single 
and partly variously grouped ; the nature of these wa. doubtful 
though they were probably concretions of some kind. ‘There 
were also other indeterminate flat and irregular masses, which 
seemed more to resemble protoplasmic substance in its mivro- 
scopical characters. 
In addition, many irregular and monad-like particles were 
seen in active movement, though there were no distinct bacteria. 
Fic. 16.—Tailed Monad and Torula Cell from a Turnip Solution which 
had been exposed to a temperature of 146°—153° C. for four hours. 
Several rod-shaped bodies zy'5y” in length (¢) were seen, however, 
resembling ordinary bacteria, except that they were unjointed and 
motionless.t+ In one of the drops examined there was a delicate 
tailed monad in active moyement—a specimen of AZonas lens, 
in fact, yon” in diameter, having a distinct vacuole in the midst 
of the granular contents of the cell. Another ovoid body was 
seen, about the same size, without a tail and motionless, though 
it contained two nuclear particles within.t 
* It was owing to the appearance of the pellicle and the seeming likelihood 
of its breaking up and sinking to the bottom if allowed to remain, as I had 
known others do, that I was induced to open this tube so early. I thought 
it possible that nothing else might form afterwards. [ felt anxious to be 
able to examine this pellicle before it got mixed with the granular matter at 
the bottom. 
+ The bacteria which appear in a simple solution of tartrate of ammonia, 
however, frequently remain motionless fora very long time, and the dacterzdia 
of Davaine are both unjointed and motionless. 
t Although these were the only bodies of this kind actually seen, it is worth 
noting that only five or six drops of about the whole ounce and a half of fluid 
were submitted to examination. This solution was undoubtedly examined 
rather prematurely. In another turnip solution which has been subsequently 
exposed in Dr. Frankland’s digester to a temperatnre of 146° C. for a shorter 
time, and which was opened on the 67th day (the details of which I shall 
