254 



NATURE 



SJan. 27, 1876 



The experiments with calcined air took another form. 

 Six years ago it was found that to render the laboratory- 

 air free from floating matter, it was only necessary to per- 

 mit a platinum wire heated to whiteness to act upon it for 

 a sufficient time. Shades, containing pear juice, damson 

 juice, hay- and turnip-juice, and water of yeast, were 

 freed from their floating matter in this way. The in- 

 fusions were subsequently boiled and permitted to remain 

 in contact with the calcined air. They are quite un- 

 changed to the present hour, while the same infusions ex- 

 posed to common air became mouldy and rotten along ago. 



It has been affirmed that turnip- and hay-infusions 

 rendered slightly alkaline are particularly prone to 

 exhibit the phenomena of spontaneous generation. 

 This was not found to be the case in the present in- 

 vestigation. Many such infusions have been prepared, 

 and they have continued for months without sensible 

 alteration. 



Finally, with regard to infusions wholly withdrawn from 

 air, a group of test-tubes, containing different infusions, 

 was boiled under a bell-jar filled with filtered air, and 

 from which the air was subsequently removed as far as 

 possible by a good air-pump. They are now as pellucid 

 as they were at the time of their preparation, more than 

 two months ago, while a group of corresponding tubes 

 exposed to the laboratory air have all fallen into rotten- 

 ness. 



There is still another form of experiment on which 

 great weight has been laid — that of hermetically sealed 

 tubes. On April 6 last, a discussion on the " Germ 

 Theory of Disease " was opened before the Pathological 

 Society of London. The meeting was attended by many 

 distinguished medical men, some of whom were profoundly 

 influenced by the arguments, and none of whom disputed 

 the facts brought forward against the theory on that 

 occasion. The following important summary of these 

 was then given : — " With the view of settling these ques- 

 tions, therefore, we may carefully prepare an infusion from 

 some animal tissue, be it muscle, kidney, or liver ; we 

 may place it in a flask whose neck is drawn out and 

 narrowed in the blowpipe-flame, we may boil the fluid, 

 seal the vessel during ebullition, and keeping it in a warm 

 place, may await the result, as I have often done. After 

 a variable time the previously heated fluid within the her- 

 metically sealed flask swarms more or less plentifully with 

 Bacte7'ia and allied organisms." 



Previous to reading this statement the author had 

 operated upon tubes of hay- and turnip-infusions, 

 and upon 21 tubes of beef, mackerel, eel, oyster, oat- 

 meal, malt, and potato, hermetically sealed while 

 boiling, not by the blowpipe, but by the far more 

 handy spirit-lamp flame. In no case was any ap- 

 pearance whatever of Bacteria or allied organisms 0I3- 

 served. The perusal of the discussion just referred to 

 caused the author to turn again to muscle, liver, and 

 kidney, with a view of varying and multiplying the evi- 

 dence. Fowl, pheasant, snipe, partridge, plover, wild duck, 

 beef, mutton, heart, tongue, lungs, brains, sweetbread, tripe, 

 the crystalline lens, and vitreous humour of an ox, herring, 

 haddock, mullet, codfish, sole, were all embraced in the 

 experiments. There was neither mistake nor ambiguity 

 about the result. One hundred and thirty-nine of the 

 flasks operated on were exhibited, and not one of this 

 cloud of witnesses offers the least countenance to the 

 assertion that liquids within flasks, boiled and her- 

 metically sealed, swarm, subsequently, more or less 

 plentifully with Bacteria and allied organisms. 



The evidence furnished by this mass of experiments, 

 that errors either of preparation or observation have 

 been committed, is, it is submitted, very strong. But 

 to err is human ; and in an inquiry so difficult and 

 fraught with such momentous issues, it is not error, 

 but the persistence in error by any of us, for dia- 

 lectic ends, that is to be deprecated. The author 



shows by illustrations the risks of error run by him- 

 self On Oct. 21 he opened the back-door of a case 

 containing six test-tubes filled with an infusion of turnip 

 which had remained perfectly clear for three weeks, while 

 three days sufficed to crowd six similar tubes exposed to 

 mote-laden air with Bacteria. With a small pipette he 

 took specimens from the pellucid tubes, and placed them 

 under the microscope. One of them yielded a field of 

 Bacterial life, monstrous in its copiousness. For a long 

 time he tried vainly to detect any source of error, and was 

 perfectly prepared to abandon the unvarying inference 

 from all the other experiments, and to accept the result 

 as a clear exception to what had previously appeared to 

 be a general law. The cause of his perplexity was finally 

 traced to the tiniest speck of an infusion containing 

 Bacteria, which had clung by capillary attraction to the 

 point of one of his pipettes. 



Again, three tubes containing infusions of turnip, hay, 

 and mutton, were boiled on Nov. 2 under a bell-jar con- 

 taining air so carefully filtered that the most searching 

 examination by a concentrated beam failed to reveal a 

 particle of floating matter. At the present time every one 

 of the tubes is thick with mycelium and covered with 

 mould. Here surely we have a case of spontaneous gene- 

 ration. Let us look to its history. 



After the air has been expelled from a boiling liquid it 

 is difficult to continue the ebullition without " bumping." 

 The liquid remains still for intei-vals, and then rises with 

 sudden energy. It did so in the case now under con- 

 sideration, and one of the tubes boiled over, the liquid 

 over-spreading the resinous surface in which the bell- 

 jar was imbedded, and on which, doubtless, germs 

 had fallen. For three weeks the infusions had re- 

 mained perfectly clear. At the end of this time, with a 

 view of renewing the air of the jar, it was exhausted, and 

 refilled by fresh air which had passed through a plug of 

 cotton-wool. As the air entered, attention was attracted 

 by two small spots of penicillium resting on the liquid 

 which had boiled over. It was at once remarked that the 

 experiment was a dangerous one, as the entering air would 

 probably detach some of the spores of the penicillium and 

 diffuse them in the bell-jar. This was, therefore, filled 

 very slowly, so as to render the disturbance a minimum. 

 Next day, however, a tuft of mycelium was observed at 

 the bottom of one of the three tubes, namely that contain- 

 ing the hay-infusion. It has by this time grown so as to 

 fill a large portion of the tube. For nearly a month 

 longer the two tubes containing the turnip- and mutton- 

 infusions maintained their transparency unimpaired. 

 Late in December the mutton-infusion, which was in 

 dangerous proximity to the outer mould, showed a tuft 

 upon its surface. The beef-infusion continued bright and 

 clear for nearly a fortnight longer. The recent cold 

 weather caused me to add a third gas-stove to the two 

 which had previously warmed the room in which the 

 experiments are conducted. The warmth of this stove 

 played upon one side of the bell-jar ; and on the day after 

 the lighting of the stove, the beef-infusion gave birth to 

 a tuft of mycelium. In this case the small spots of peni- 

 ciUium might have readily escaped attention ; and had 

 they done so we should have had three cases of " spon- 

 taneous generation " far more striking than many that 

 have been adduced. 



{To be continued.) 



NOTES 

 M. E. QtJETELET has issued a Notice giving a brief account 

 of the recent progress of the Brussels Observatory, which has 

 been estabhshed only in the face of great difficulties. In 1833 

 meteorological observations were commenced to be made, and a 

 few years after astronomical observations were added by the 

 elder Quetelet. The work v/hich is at present being carried on 

 has for its object a general revision of the variable stars. Seventy 



