SPOXTAXEO US GENERA TIOK 



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the all-prevailing rule is to accept as facts the 

 announcements — not necessarily the inferences — 

 of a scientific inquirer until his conclusions have 

 been displaced by other investigators who have 

 repeated his experiments with scrupulous accu- 

 racy, and have arrived at discordant results But 

 though the work of an isolated individual must 

 he prima facie accepted as trustworthy, it proper- 

 ly commands a far larger measure of confidence 

 after it has been confirmed by others, and acquires 

 the highest title to respect when it has been chal- 

 lenged and successfully repeated in the presence 

 of an able opponent. In making our choice, 

 therefore, of investigations to be specially de- 

 scribed, we propose, whenever practicable, to put 

 in the front rank those almost judicial experiments 

 which have stood fire face to face with an adver- 

 sary, and next in order to class those which have 

 been successfully repeated by independent work- 

 ers ; resorting to what we may call solitary in- 

 vestigations in those cases only where no con- 

 firmed experiments exist, and paying but slight 

 regard to mere general statement of results when 

 the experimental details have not been furnished. 

 Dealing in this way with the evidence on both 

 sides, it may be practicable without exceeding due 

 limits to present a fairly representative array of 

 the most valuable materials for forming a rational 

 estimate of the position of the controversy. It 

 makes no great difference whether the work on 

 one side or the other is brought first under re- 

 view, but as the supporters of spontaneous gen- 

 eration maintain the assertion that, after com- 

 plete destruction and exclusion of germs, life will 

 sometimes display itself, while the case of the 

 germ-theorists amounts to a simple denial of 

 this proposition, the more convenient arrange- 

 ment seems to be, first to weigh the evidence in 

 support of the positive view, and then to set 

 against it the negative testimony of its opponents. 

 First, then, let us call Dr. Bastian into court, and, 

 pursuing the course already indicated, the reader's 

 attention shall be first directed to a remarkable 

 series of experiments which he performed in con- 

 cert with Dr. Burdon-Sanderson, then a resolute 

 opponent, and then and now one of the very 

 ablest investigators of this branch of biology. 



But before quoting the details of the Bastian- 

 Sanderson series of experiments, which we shall 

 do from Dr. Sanderson's narrative published in 

 Nature, on the 8th of July, 1S73, a few words are 

 needed to explain the circumstances out of which 

 this special investigation grew. Dr. Bastian had 

 published an account of a vast amount of work 

 8 



which he had done upon this subject during a 

 continuous investigation of several years. The 

 general nature of his experiments, so far as they 

 related to the possibility of the de novo origination 

 of life, was this : He took a small glass retort- 

 shaped flask, partly filled with some infusion of 

 organic matter, and drew out the tube of it to an 

 almost capillary orifice. Lie then boiled the in- 

 fusion for five minutes or more with sufficient 

 activity to spurt out some of the contents at in- 

 tervals, so as to wash the whole interior surface 

 of the flask with the boiling liquid. Then, while 

 the ebullition was still going on, he sealed the 

 tube hermetically in a blowpipe - flame. The 

 vacuum in the tube was tested as a safeguard 

 against errors of manipulation, the flask was kept 

 in a warm temperature, and the appearance or 

 non-appearance of putrefaction and bacterial life 

 was noted. These experiments were multiplied 

 with a great number of different substances and 

 with results by no means uniform. Some few in- 

 fusions were found, as a rule, to remain clear and 

 sterile after a long period of incubation. "With 

 other materials putrefaction occurred only in a 

 moderate percentage of the specimens. Another 

 class of infusions w r ould always give a very large 

 proportion of fertile examples together with a few 

 that remained permanently sterile, while there 

 were some specially favorable substances which 

 never, or scarcely ever, failed to develop bacterial 

 putrefaction within at most a few days. Some- 

 times, of two flasks of the same infusion treated, 

 so far as could be ascertained, in precisely the 

 same manner one would putrefy while the other 

 remained pure, but in the course of his long series 

 of investigations Dr. Bastian succeeded in dis- 

 covering many of the conditions most favorable 

 to the development of life. Although all the in- 

 fusions employed, when once inoculated with the 

 smallest drop of fluid containing bacteria, or in 

 general when exposed to ordinary air, were cer- 

 tain in a brief period to become turbid, from their 

 rapid multiplication, they were by no means 

 equally prone to putrefy when boiled and pro- 

 tected in the sealed retorts. Urine, for example, 

 though presumably as apt to engender life as any 

 organic fluid that could be suggested, was for a 

 long time thought by Bastian, as by his predeces- 

 sors in the inquiry, to be absolutely proof against 

 corruption if boiled and protected. Some meat- 

 infusions offered less resistance to vital transfor- 

 mation, but still gave varying and sometimes 

 small percentages of positive results. Others, 

 again, such as hay and turnip infusions, yielded 

 readily, though not invariably, to the putrefactive 



