SPONTANEOUS GENERATION: A LAST WORD. 



507 



sible guesses based solely on the germ-theorists' 

 way of thinking, before he abandons Liebig's fer- 

 tile idea, supported by Gerhardt and others, that 

 tbe mere organic matter of the air can engender 

 fermentative changes in suitable fluids, leading 

 though it may, among other phenomena, to a new 

 birth of living particles. This, too, the reader 

 will observe, is a very different notion concerning 

 the origin of such new living particles from that 

 which Prof. Tyndall persists in attributing to me, 

 viz., the absurd idea that mere dead particles from 

 the air are themselves 'miraculously kindled into 

 living things.' " 



It is to be hoped that the reader will be able 

 to observe the difference to which his attention 

 is here directed. For my own part I am grateful 

 for the explanation, such as it is, which, in view 

 of the writer's previous utterances, was by no 

 means unnecessary. It does not, it is true, quite 

 abolish the " miracle," but it changes the form 

 thereof. It is not, we now learn, the dead at- 

 mospheric particles themselves that are kindled 

 into life; it is, on the contrary, the dead particles 

 of the liquid that are kindled into life by the dead 

 particles of the air. The former, we are told, is 

 an " absurd idea," while the latter, I suppose, is 

 thought a sweetly reasonable one. Thus, the dis- 

 cord persistently raised by me is finally resolved. 

 The "reader," if I might claim his attention for 

 a moment, will observe the frictionless way in 

 which this " new birth of living particles " in the 

 liquid, begotten, be it remembered, by the dead 

 particles of the air, glides in as a small corollary 

 to Liebig's " fertile idea." There are people 

 among us who, it is alleged, can produce effects, 

 before which the discoveries of Newton pale. 

 There are men of science who would sell all that 

 they have, and give the proceeds to the poor, for 

 a glimpse of phenomena which are mere trifles 

 to the " spiritualist." In like manner, while no 

 discovery of the age would bear comparisoH with 

 this "new birth of living particles," it is a mere 

 commonplace occurrence to our fortunate hete- 

 rogenist. 



My respondent scatters through his article 

 words and phrases which he intends to have an 

 effect, if not a meaning. He labels proofs as 

 " assumptions," ocular demonstrations as " pos- 

 sible guesses," and propositions backed by all 

 the knowledge of Nature which we possess as 

 the outcome of arbitrary prejudice. He speaks 

 of my "setting the seal upon Nature's possibili- 

 ties " when I am merely setting it upon his own 

 illicit wanderings. Indeed, he plainly shows him- 

 self to be unacquainted with the real basis of 

 scientific inference. Let us consider a special 



case, over which he has loudly sounded the argu- 

 mentative timbrel. In my January article I refer 

 to Pouchet, fairly, I trust, appreciating his learn- 

 ing and his strength, but quoting his own words 

 to indicate the leaning of his mind when he be- 

 gan his researches on heterogeny. My respon- 

 dent retorts that I show " an even more obvious 

 bias in the contrary direction ; " and, to make 

 his point good, he publishes a mutilated para- 

 graph from one of my letters. The full text of 

 the paragraph I here restore : 



" Dr. Bastian says that two interpretations of my 

 facts are equally admissible. He is again wrong ; 

 there is but one interpretation possible. An inter- 

 pretation which violates all antecedent knowledge 

 is undeserving of the name. All our experience 

 of the method of Nature goes to show that, if a 

 sown particle sprout into a plant, the particle is 

 proved thereby to be the seed of that plant. The 

 inference that a particle which, when sown, pro- 

 duces a thistle is the seed of the thistle, is not 

 surer than the inference that the particles described 

 in the Times as rising in clouds from shaken hay 

 embrace the seeds of bacteria ; while, to infer that 

 the thistle is the offspring, not of a living seed, but 

 of dead, unrelated organic matter, is not more re- 

 pugnant to right reason than the so-called second 

 interpretation of Dr. Bastian, which ascribes such 

 definite organisms as hay-bacillus to dead dust." 



This, I submit, is reasoning of a perfectly 

 sound and wholesome kind. My respondent, how- 

 ever, italicizes one obnoxious line of the para- 

 graph, omits some others, and deduces from the 

 whole that I have set my presumptuous seal upon 

 the " possibilities of Nature," and done other 

 foolish things. I think it will not be difficult to 

 make this matter plain to the readers of the 

 Nineteenth Century. The smallest organisms 

 which the microscope has hitherto revealed are 

 grouped together under the common name of 

 bacteria. They differ from each other both in 

 size and shape, some being globular, some staff- 

 like (whence the name), some having the form of 

 fine filaments, some mobile, and some still. In 

 the staff-like bacteria, the usual mode of prop- 

 agation and multiplication is bisection. The 

 " staff" is nipped at its centre, the nip deepens, 

 and finally the bacterium is divided into two 

 halves, which lengthen and are bisected in their 

 turn. According to a calculation of Dr. Bur- 

 don-Sanderson, this process enables 17,000,000 

 individuals to proceed in twenty -four hours 

 from a single ancestor. In the case, however, of 

 certain large bacteria, which, because they are 

 large, have been more thoroughly examined than 

 the others, the rods or filaments are observed to 



