The modes of origin of lowest organisms

25

If his reasonings can be shown to be quite inconclusive, and if his results can be otherwise explained, some people may, at last, begin to recognize that their blind and mistaken faith in M. Pasteur’s work has been somewhat misplaced.

26

M. Pasteur attempted to make a distinction in the case of slightly alkaline or neutral fluids (loc. cit., pp. 60–65). I have endeavoured to show the untenability of his conclusion in ‘Nature,’ 1870, No. 37, pp. 224–227.

27

‘Nature,’ 1870, No. 35, p. 171.

28

I always employ a solution of gum mastic and bismuth in chloroform. If a different varnish be employed, it is of course necessary to ascertain whether its application is injurious to the enclosed Bacteria.

29

If an unboiled specimen of milk be mounted, a multiplication of living particles takes place here and there amongst the fat globules, just as the multiplication of Bacteria occurs in a vegetable infusion; but in the boiled specimen no trace of such multiplication can ever be detected.

30

Those particles which come to rest, in such cases, are always in contact with one or other of the contiguous surfaces of glass.

31

The specific gravity of the fluid being constant. Where this is dense or viscid, as with glycerine, Brownian movements do not occur at all.

32

In the proportion of ten grains of neutral ammonic tartrate, with three grains of neutral sodic phosphate, to an ounce of distilled water.

33

It was necessary to boil the solution first, in order to destroy any living things or dead ferments which it might contain. It must contain one or the other, because an unboiled solution of this kind, in a corked bottle about half full, will always become turbid; whilst, after it has been boiled, it may be kept indefinitely under similar conditions without becoming turbid.

34

The proportion was one drop of the fluid, opaque with organisms, to an ounce of the clear solution.

35

Into which a piece of glass tube had been slipped to prevent collapse.

36

Allowing even five minutes for the temperature of the 1 oz. of fluid to become equal to that of the bath, it would then have remained exposed to this amount of heat for about ten minutes.

37

Fluids which had remained sterile would always, in the course of thirty-six or forty-eight hours after inoculation with living Bacteria, become more or less turbid.

38

There is, however, another point of extreme interest in connection with these experiments, bearing upon the supposed universal distribution of “germs” of Bacteria and other organisms, which I will now mention. One of the flasks, which had been exposed to 140° F., and which had been hermetically sealed at this temperature, had its neck cracked (accidentally) about half an hour afterwards. Thinking it would be as well, notwithstanding this, to keep it and observe the result, its bulb was immersed in the same water-bath with the other flasks which had been prepared at the same time. Whilst the fluid in one of these which had been exposed to a heat of 131° F., became turbid in the course of a few days, this, which had been exposed to a heat of 140° F. and whose neck was also extensively cracked, remained quite clear for seven days, although to such an extent exposed to the access of germs. Its eminent suitability for nourishing the germs of such organisms was also shown, because, on the seventh day, the fluid being still clear, the blade of a penknife was dipped into it, after having been previously immersed in a solution containing living Bacteria and Torulæ, and in thirty-six hours after this inoculation, the fluid had become turbid, owing to the presence of myriads of these organisms. So that even where obvious cracks occur, and the vacuum is altogether impaired by the consequent inrush of air, such air does not necessarily carry with it germs of Bacteria– which have been supposed to be universally diffused, and capable of passing through cracks so minute as to be invisible. These results, important as they are, have not at all surprised me, because one may frequently find a previously boiled solution of the kind under consideration, remaining free from turbidity for two weeks or more, although the neck of the flask has been merely covered by a loose paper-cap (see p. 30 (#Page_30)).

39

‘Nouvelles Expériences,’ etc., 1864, p. 38.

40

‘American Journal of Science and Arts,’ Oct. 1867.

41

During nearly the whole of the time the temperature was kept at 113° F. It only rose to the higher temperature for about ten minutes.

42

The Bacteria and Vibriones with which Professor Wyman experimented were derived from different sources; and so far as I also have been able to ascertain, the Bacteria of different fluids are similarly affected by exposure to similar degrees of heat. Thus, if on the same slip, though under different covering glasses, specimens of a hay infusion, turbid with Bacteria, are mounted, (a) without being heated, (b) after the fluid has been raised to 122° F. for ten minutes, and (c) after the fluid has been heated to 140° F. for ten minutes, it will be found that, in the course of a few days, the Bacteria under a and b have notably increased in quantity, whilst those under c do not become more numerous, however long the slide is kept. Facts of the same kind are observable if a turnip infusion, containing living Bacteria, is experimented with; and the phenomena are in no way different if a solution of ammonic tartrate and sodic phosphate (containing Bacteria) be employed instead of one of these vegetable infusions. The multiplication of the Bacteria beneath the covering-glass, when it occurs, is soon rendered obvious, even to the naked eye, by the increasing cloudiness of the film.

43

‘Compt. Rend.,’ t. lxi. p. 1060.

44

When boiled solutions, containing mannite, with a little nitrate and phosphate of ammonia, were employed, they always remained sterile. Similar negative results followed the employment of ox-gall. Of three decoctions of beef with which M. Meunier experimented, the two stronger of them were found to contain swarms of Bacteria in about twelve days. Of three other flasks containing boiled urine, two also proved fertile.

45

I have employed flasks of about 1 1/2 oz. in capacity, provided with necks two feet in length. In each case, after the flask has been half filled with the fluid, the neck has been bent eight times at an acute angle.

46

These are the only experiments which I have performed with the very long plugs of cotton-wool, though in other previous trials with plugs about 1 1/2 in. long, I have several times obtained positive results.

47

When infusions have been employed, these have all been made as strong as possible, and have been filtered before use. Warm water has been added in quantity just sufficient to cover the substance to be infused (cut into very small pieces), and the mixture has then been kept at a temperature of from 110°–130° F. for three or four hours.

48

Flask still in my possession, unopened.

49

Flask still in my possession, unopened.