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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



for supposing that the physical or chemical con- 

 ditions of the earth were more favorable to life- 

 evolution in the past than in the present. I 

 recoil from a gratuitous assumption of discon- 

 tinuity in Nature, and, if I were permitted to 

 discern the movements of ultimate molecules, I 

 should expect to behold primordial forms of life 

 incessantly springing up from the same so-called 

 dead but potentially living matter which, on any 

 hypothesis, must at one time have developed 

 them." 



Analogical reasons, which are supposed to 

 recommend these rival hypotheses, have been 

 accumulated by their partisans with wonderful 

 assiduity. On the one side, it is urged that all 

 the more developed beasts and birds, fishes and 

 plants, are multiplied by offshoots from a living 

 parent, and that it is a relief to the mind to 

 thrust back into a remote antiquity a process 

 which obliterates the exaltation of living creat- 

 ures over dead material. On the other, it is ob- 

 served that the constant conversion of dead food 

 into living protoplasm is the very condition of 

 vital existence ; that the earliest living products 

 must have arisen by a similar process, without 

 the stimulus afforded by contact with living cells ; 

 and that no reason can be assigned why the forces 

 of Nature should be powerless now to do what 

 unquestionably they did in the so-called infancy 

 of the world. And arguments from analogy have 

 unfortunately been reenforced by arguments from 

 authority, and this almost as freely by the one 

 school as by the other. For fashion may be 

 traced in the world of science no less than in the 

 world of society, and fashion has more than once 

 changed sides with singular caprice in her esti- 

 mate of the vital controversy. One of the first 

 modern propounders of the maxim Omne vivum 

 ex vivo was denounced as a wicked contravener 

 of Scripture, which in his day was supposed to 

 favor the theory of spontaneous generation. The 

 later expositors of this once orthodox doctrine 

 have been impartially condemned as materialistic 

 enemies of natural religion. But all such carping 

 passes by the truly scientific mind as idle wind. 

 No authority, except the authority of experi- 

 mental work, can weigh a feather in the balance. 

 No a priori reasoning can give the victory to 

 either creed. The deep mystery of the subject 

 defies all shallow treatment ; but not the less is 

 it true, as Sir William Thomson has said with 

 respect to this very question, that " Science is 

 bound by the everlasting law of lionor to face 

 fearlessly every problem which can fairly be pre- 

 sented to her," and we may add that she is 



bound to face this problem cased in the same 

 panoply of candor and armed with the same 

 weapons of inductive investigation with which 

 she has conquered all the domain which she now 

 holds. Nor is there anything in the enterprise 

 to justify despair. Once be sure that you can 

 isolate a portion of dead matter, and the riddle 

 is solved. If, after repeated and patiently varied 

 trials, life uniformly fails to appear, the hy- 

 pothesis of a single act, or at any rate a single 

 epoch, of life-evolution becomes almost irresisti- 

 ble. If, on the other hand, life shows itself in a 

 sufficient number of instances to exclude the 

 probability of accidental error, the theory of 

 what is called spontaneous generation must be 

 accepted as a scientific truth. 



That the controversy resolved itself into this 

 purely experimental question has been frankly 

 recognized ever since the time when experience 

 was acknowledged to be the only basis of natural 

 science. For many generations an almost un- 

 broken succession of inquirers have striven to 

 perform the crucial experiment which we have 

 indicated, and, though sometimes one and some- 

 times the other party has for a time claimed vic- 

 tory all along the line, the struggle still maintains 

 itself as fiercely as ever. Redi's inferences, ad- 

 verse upon the whole to spontaneous generation, 

 stood their ground for a century, till they were 

 displaced by Needham's experiments. Needham, 

 in his turn, was discredited by Spallanzani ; and, 

 in our own day, the battle has been continued 

 by Pasteur and Pouchet in France ; by Bastian, 

 Lister, Sanderson, and Tyndall, in England ; by 

 Huitzinga, Cohn, Klebs, and Billroth, in Holland, 

 Austria, and Germany ; by Mantegazza, Cantoni, 

 and Oehl, in Italy ; by Wyman, in America ; and 

 by other inquirers, too numerous to mention, in 

 all parts of the civilized world. The multitude 

 of experiments which have been tried to eluci- 

 date this single point is almost countless, and as 

 yet no generally accepted conclusion has been 

 reached. It is such a simple matter to state the 

 conditions of the requisite investigation that one 

 is tempted at first sight to marvel at the persist- 

 ency of the contest. There is absolutely nothing 

 to be done but to take dead matter, isolate it 

 from all contact with life, place it under favorable 

 conditions for development, and watch the result ; 

 and yet this task has seemed to defy the efforts 

 of as keen a body of inquirers as ever attacked 

 any problem of Nature. If we look a little closer 

 into the matter, we shall perhaps cease to wonder 

 at the discordant conclusions which rival savants 

 have deduced. We are too apt to forget that an 



