perfectly intelligible that inasmuch as organic
matter is said to form the indispensable condition
for the development of the eggs, it is only in the
vessel containing such matter that the eggs will
develops; but why are they not also visible as eggs
in the other vessels? why are not the animalcules
themselves visible there, as they were in the water
examined by M. Quatrefages? If both eggs and
animalcules are blown about like dust in the air,
it is an immense stretch of credulity to believe
they will only be blown into the vessel containing
organic matter; but the opponents of Spontaneous
Generation go further even than this, for they
declare these dust-like animalcules will be blown
into a closed vessel, if it contain organic matter,
but not into several open vessels, if they only contain distilled water.
M. Quatrefages is on better ground when he rejects the evidence, long supposed to be so weighty, of parasitic animals. He refers to the modern investigations which have not only made the generation of these parasites intelligible, but in many cases have demonstrated it. M. Pouchet’a reply is feeble, and unworthy of a physiologist of his eminence. He doubts the truth of the results obtained in Germany, Italy, and Belgium: “the monopoly of which,” he adds, “has, by a strange anomaly, belonged to foreigners.” Because France has not the honour of this splendid discovery, the Frenchman begs to doubt its value! Every physiologist, however — not French — will be ready to admit that whereas the parasitic animals formerly furnished the advocates of Spontaneous Generation with their most striking illustrations, the investigations of Von Siebold, Van Beneden, Küchenmeister, Philippi, and others, have entirely changed the whole aspect of the question, and given the opponents of Spontaneous Generation new grounds for believing that in time all obscurities will be cleared away, all contradictions explained.
In conclusion, I must say that as far as regards the particular discussion, M. Pouchet seems to me to have the best of it. Their objections to his experiments are all set aside. If the facts are as he states them — and his antagonists at present do not dispute the facts — their criticisms go for very little. They have not shown it probable that any germs could have been present, under the conditions stated by him. Are we, then, to accept Spontaneous Generation as proven? By no means. It is very far from proven. The massive preponderance of fact and argument against such an hypothesis forces us to pause long before we accept it. What M. Pouchet has done is to destroy many of the arguments against Spontaneous Generation, and to have devised experiments which may finally lead to a conclusion. It is still on the cards that some source of error as yet overlooked vitiates his experiments; but until that error has been detected, he must be considered to have on his side the evidence of experiment, whereas we have on our side the massive evidence of extensive inductions. His experiment may be conclusive, and an exception to the general law will thereby be established But it may also, on further investigation, turn out to be illusory; some little oversight may be detected which will rob the experiment of all its force.
Perhaps you will ask why this suspicion should be entertained? Why ought we not to accept M. Pouchet’s statement with confidence, although it does contradict our inductions? The reason can only be, that the massive weight of these inductions naturally predisposes the mind to believe that it is more probable the experiment which contradicts them should be misconceived, than that they should be contradicted. Two years ago I became acquainted with an observation made by Cienkowski, the botanist, which seemed finally to settle this question of Spontaneous Generation, to place the fact beyond doubt, because it caught Nature in the act, so to speak, of spontaneously generating. Cienkowski’a statement is as follows: If a slice of raw potato be allowed to decompose in a little water, it will be found, after some days, that the starch grains have a peculiar border, bearing a strong resemblance to a cell-membrane. This shortly turns out to be a real cell-membrane, and is gradually raised above the starch-grain, which grain then occupies the position of a cell- nucleus. Thus, out of a grain of starch, a cell has been formed under the observer's eye. Inside this cell, little granular masses are developed, which begin to contract. Finally, minute eel- like animalcules are developed there, which bore their way through the cell-wall into the water.
Funke in his report of this observation, which he says, he has verified, asks, how is it possible to deny Spontaneous Generation here? Before our eyes a grain of starch becomes a cell, in that cell are developed living forms, which bore their way out.
The reader will imagine the sensation which such an observation created. He will agree with Funke, as I did, that if the fact were as he stated it, all discussion was at an end. But was the fact as stated? I tried in vain to verify it. Not less than twenty separate potatoes were employed, always in conjunction with ordinary starch, as a point of comparison; but although the animalcules were abundant enough, I never could satisfy myself of the first and all-important step, namely, the formation of a cell wall round the starch-grain. This was the more distressing, because it is at all times unpleasant to be unable to verify an observation, especially one made by a careful and competent observer, and described in precise terms.
I could not reject what Cienkowski had positively affirmed, and Funke positively confirmed, and was willing to suppose that there was some necessary condition in the observation which I had not fulfilled. On the other hand, I could not reject a doctrine on the strength of a fact about which any doubt was permissible. In this state of suspense I had the satisfaction of hearing from Professor Naegeli, the celebrated microscopist, that he too had been baffled at first in the attempt to verify this observation, but that, after nearly a hundred trials, he had succeeded. He positively confirmed all the statements Cienkowski had made. But, from that moment, my suspense vanished. If the phenomenon was of such rare occurrence, there were reasons for suspecting some other explanation
than that of Spontaneous Generation. What the source of the error was might not be easily divined;