NARROWING THE EXPERIMENTAL ISSUE. 



123 



obtained by different observers, and a settlement 

 of the question seemed further off than ever. 

 But, about the middle of last year, Dr. Bastian 

 earned the gratitude of biologists by narrowing 

 the point at issue, and giving, for a time at least, 

 a definite direction to future experiments. He 

 announced, at the meeting of the Royal Society 

 on the 15th of June, 1 that he had discovered the 

 precise conditions under which living organisms 

 were infallibly produced in certain putrescible but 

 sterilized organic fluids. If this supposed discov- 

 ery were a real one, its importance could hardly 

 be over-estimated ; for if once the conditions re- 

 quisite for development of life de novo in an or- j 

 ganic fluid were ascertained, it would be but one 

 step further to imitate those conditions in a manu- 

 factured fluid of known composition, and thus to 

 gain some conception of the way in which the 

 first germs of life may have originated on the 

 earth. The theory of evolution would thus be 

 complete at one end of the scale of being, and 

 would receive a confirmation of its truth which 

 "none of our enemies would be able to gainsay 

 or to resist." 



The needful conditions for the spontaneous de- 

 velopment of life in boiled organic fluids are, ac- 

 cording to Dr. Bastian, the neutrality or slight 

 alkalinity of the fluid, or its maintenance at a tol- 

 erably high temperature (11 5°-120° Fahr.). He 

 placed his putrescible fluid (urine) in glass re- 

 torts, into the necks of which he introduced a 

 small sealed glass tube drawn out to a fine point 

 and containing enough potash solution to neu- 

 tralize the fluid, the potash having been previous- 

 ly heated to the temperature of boiling water. 

 After the introduction of the potash-tube the re- 

 tort and its contents were subjected for some 

 minutes to the boiling temperature ; the neck of 

 the vessel was sealed during ebullition, and, after 

 cooling, the potash was liberated by a shake suffi- 

 ciently violent to break the capillary tube. 



Under these circumstances Dr. Bastian found 

 that in every case the fluid swarmed with bacteria 

 after a longer or shorter time ; while no organ- 

 isms were developed if it remained acid, or if an 

 excess of alkali had been added. Even under 

 these latter circumstances, however, a copious 

 development of bacteria was insured by keeping 

 the fluid at a temperature of 122°. 



This is Dr. Bastian's case. But it will be ob- 

 served that he failed to " mak sicker " in two 

 important points : in the first place, there was 

 no proof that the fluids in question would not 



1 " Proceedings of the Royal Society," 18T6, vol. xxv., 

 No. 172. 



have developed bacteria without the addition of 

 the potash ; and, secondly, the potash was heat- 

 ed only to the temperature of boiling water, a 

 temperature which, though amply sufficient to 

 kill adult bacteria, has been proved, in many 

 cases, to leave their germs unslain. It became 

 essential, then, to repeat the experiments, allow- 

 ing the fluids to stand sufficiently long, before 

 adding potash, to make it tolerably certain that 

 no organisms would be developed without the ad- 

 dition of the alkali, and to heat the potash to a 

 temperature considerably above the boiling-point 

 of water, so as to insure the complete destruc- 

 tion of the most enduring microphyte-germs. 



Experiments with these necessary precautions 

 have lately been made by Prof. Tyndall, and Dr. 

 W. Roberts, of Manchester, and their results 

 seem to demonstrate, conclusively enough, the 

 fallacy of Dr. Bastian's conclusions. 



Dr. Roberts's experiments 1 were conducted 

 in the same manner as Dr. Bastian's, with one or 

 two important modifications. In the first place, 

 the tube containing the proper quantity of potash 

 for neutralization of the fluid was heated, in an 

 oil-bath, to a temperature of 280° Fahr., 68° 

 above the boiling-point of water ; secondly, after 

 the flask containing the boiled fluid with its con- 

 tained potash-tube had been hermetically sealed 

 — of course during ebullition — it was allowed to 

 stand in a warm place for a fortnight, and thus 

 prove its complete sterility. The potash-tube 

 was then broken, and the flask exposed to a tem- 

 perature of 115°, and afterward to one of 122° ; 

 that is, the fluid was exposed to the very condi- 

 tions which, according to Dr. Bastian, are most 

 potent in inducing spontaneous generation. Nev- 

 ertheless, every one of the flasks was found to 

 be absolutely sterile. It must be observed that 

 not one of the essential conditions was altered — 

 potash is no more affected by the temperature 

 of 280° than by that of 212° ; the putrescible 

 fluid was only boiled, under the ordinary atmos- 

 pheric pressure, for five minutes, so that its com- 

 position could have been in no way altered, and 

 yet the results obtained were, without exception, 

 negative. 



In Prof. Tyndall's 5 experiments the same 

 course was adopted, except for the fact that the 

 potash was heated only to 220° Fahr. instead of 

 280°. Again the results were negative. Prof. 

 Tyndall, as usual, brings forward a " cloud of 

 witnesses " to prove his position, and says, " The 

 experiments have already extended to one hun- 



1 Proceedings of the Royal Society, vol. xxv., No. 176. 



2 Loc. cit., p. 457. 



