NA TURE 



[May 7, 1874 



edition of his work on the Sun, on an enlarged scale. He has 

 quoted so largely from Mr. Lockyer's ' Solar Physics ' that an 

 intended translation of this work is abandoned for the present." 



I have the honour to inform you that the complete original of 

 my second edition has been in the hands of M. Gauthier for 

 mort than a month, so far as that part which may have some- 

 thing in common with Mr. Lockyer's work is concerned, and that 

 I had not seen Mr. Lockyer's work until a fortnight ago, when 

 I bought it from M. Loescher here in Rome. Mr. Lockyer of 

 course is quo'ed, but only from his original memoirs, and not 

 from his new publication, r.or in such a manner that his 

 publication will render my work useless. 



Rome, March 23 P. R. Secchi 



[The following explanation has been sent us by the Paris cor- 

 respondent who furnished us with the note referred to by Father 

 Secchi :^ 



" I was told by his (P. Secchi's) editor himself, when I spoke 

 to him about publishing a French edition of Mr. Lockyer's 

 'Solar Physics,' the substance of what I have written to you. 

 I think that the note I have written is a recommendation of 

 Father Secchi's work ; but not so his statement that he did not 

 possess ' Solar Physics ' until it was too late to use it. There 

 is nothing whatever dishonourable in quotation." — Ed.] 



Spontaneous Generation Experiments 



Since October 1870 I have, as opportunity offered and other 

 work permitted, made a series of experiments bearing on the 

 question of spontaneous generation. They seem to me to tell so 

 plain a story that I am an.'iious to relate it. 



The thoughts ,vhich led to the experiments were briefly 

 these :^ 



The occasional or even frequent presence of living growths in 

 fluids after they have been exposed to a temperature of 212° F. 

 and are contained in closed tubes or flasks is rather an indication 

 of the imperfection of a method than the proof of a theory ; 

 for under like circumstances living organisms ought either 

 always or never to develop ; the conditions being uniform, the 

 results should be uniform. 



When the tubes are closed at a blow-pipe flame after boiling, 

 steam cannot be escaping from the aperture at the time of actual 

 closure, and it is conceivable that in the momentary collapse of 

 the contents which then occurs some atmospheric air containing 

 organic matter may pass into the tube and invalidate the experi- 

 ment. 



The contained air, if any there be after the sealing of the 

 tubes, must be vastly rarefied, and the ordinary atmospheric con- 

 ditions, other than purity, which are essential, must be absent or 

 greatly modified. 



I attempted to devise an experiment which would be free from 

 these possible sources of error ; one in which the atmospheric pres- 

 sure should be normal, in which the physical structure of the air 

 should be unaltered, and in which there should be no chance of or- 

 ganic contamination after heating. Further it seemed a good thing 

 to be able to show at the same time and in the same apparatus 

 two distinct specimens of the boiled fluid, the one exposed only 

 to cleaned air, the other exposed also to common air ; and also 

 to use a fluid which would indicate to the naked eye by change 

 ot colour, or of clearness, or of consistence, the time at which 

 living growths made theur appearance. 



The latter condition was secured by using a fluid (for the idea 

 of which I am indebted to Mr. lleisch's experiments on water- 

 impurities) compo.ed of 10 cc. of urine, i gramme of white 

 sugar, and 90 cc. of distilled water. This when boiled and 

 filtered is a clear transparent liquid, which becomes milky on the 

 occurrence of organic growth during fermentation in thirty to 

 forty hours, according to the heat to which it is exposed. 



The other conditions were effected by using a glass tube of the 

 shape of the capital letter M, with curved bends instead of 

 the angles ; a tube which may be described as having four 

 straight legs joined to each other by two loops on the upper side 

 and one on the lower ; the first leg closed and the last leg open 

 and short. 



This tube, so bent, was made very hot, so as to expel as much 

 air as possible from it ; the open end was then plunged into the 

 boiled and filtered urine-sugar fluid, and such a quantity allowed 

 to flow in on the cooling cf the tube as left the first, second, and 

 third legs about half full when the tube was held upright. The 

 tube was again heated to the boiling of the contained fluid in 

 order to expel as much air as possible by the generation of 



steam. It was then allowed slowly to cool, so that the first leg 

 was about one-third filled with fluid ; and such an amount was 

 left in the lower loop as would rise in the second and third legs 

 to about the same exfent as the tube cooled (and the cooling was 

 designedly prolonged) ; air passed through the fluid in the lower 

 loop to fill the sjace in the fir. t upper loop, between the two 

 masses of fluid, left vacant by the condensation of steam. 



The tube was then hung up, away from direct sunlight, and 

 exposed to the ordinar)' charges of temperature of my study. 



If I have been able to describe intelligibly this very simple 

 matter, it will be seen that I had here two portions of the same 

 fluid separated from each other ; both having been heated to the 

 same temperature and both exposed to atmospheric air. 



The conditions were precisely similar with one exception ; in- 

 tentional and crucial. The air in the first upper loop, to which 

 air only the fluid in the first leg was exposed, had passed 

 through and been washed by the fluid in the lower loop ; and 

 the fluid of this loop was on one side exposed to the washed air 

 and on the other side to the ordinary atmosphere. 



In experiments with this apparatus the phenomena were, in eight 

 cases, as follows : — On the second or third day the fluid in the 

 loop was milky, and the fluid in the first leg was bright. At the 

 end of a week, a month, four months, indeed as long as the tube 

 was kept, the one continued clear, the other was turbid. At 

 the expiration of a time, varying in different experiments from 

 four days to four months, I tilted over the least drop of the tur- 

 bid fluid in the loop into the clear fluid in the first leg, when at 

 once the milkiness began, and in a day the whole of the leg fluid 

 was turbid also. 



In many cases I examined the two fluids, clear and turbid, 

 with a twelfth-inch object-glass, and found Bacteria in the tur- 

 bid fluid ; nothing in the clear fluid. 



Twice I left (once unintentionally, once intentionally) so little 

 fluid in the loop that, there being a small aperture, it did not 

 fulfil its purpose as a filter and a valve, and in both cases the 

 two masses of fluid became turbid at the same lime. 



In six other experiments I used urine ; in four instances the 

 loop fluid showed symptoms of putrefaction, and became turbid 

 in four or five days, but the leg fluid remained clear. On the 

 closure of the experiment, at varying periods from a week to 

 four months, the bright urine appeared, on microscopic examina- 

 tion, to contain no organic growth, but underwent putrefaction 

 as ordinary urine when exposed to the air. 



In the two other experiments both urines putrefied at the 

 same time. In one case I hastened the cooling by cold ; In the 

 other I left very little fluid in the loop. 



In four experiments I used Dr. Charlton Bastian's turnip-cheese 

 fluid. In all cases the solution was milky when made ; twice it 

 was filtered'and twice unfiltered, and in all cases, when examined 

 by the microscope after the lapse of some days or weeks, the 

 fluid in both leg and loop contained organic growth. 



The experiments on urine and urine-sugar fluid show, in my 

 view, both positively and negatively, that there is something in 

 the ordinary air which is a necessary condition of the origin ot 

 organic growth in these liquids. 



Positively this position is demonstrated when, after six months, 

 the fluid in contact with unwashed air is seen to be full of 

 organic growth, and the fluid in contact with washed air is still 

 unch.anged. 



Negatively it is supported when both fluids are seen to grow 

 turbid at the same time from imperfect washing of the air, by 

 reason of too rapid cooling or too scanty a supply of fluid for 

 the washing. 



The experiments with Dr. Bastian's turnip-cheese fluid were 

 for some time a puzzle to me, and made me fear that there was 

 an undetected fallacy in my other experiments. But now it is 

 clear that the contradiction is only apparent. Dr. Burdon San- 

 derson has shown that this fluid contains within itself the ele- 

 ments of organic growth which are not destroyed at 212° F., 

 the temperature_at which my experiments were necessarily con- 

 ducted. 



I am anxious not to press these experiments unduly, but they 

 seem to me to range themselves uneLjuivocally in opposition to 

 the theory of spontaneous generation ;_although they touch no 

 great extent of the subject. 



That the sometliing in the ordinary air necessary for the origin 

 of organic growth in the fluids used is a gaseous impurity of the 

 air is supported by no fact of which I am aware ; but whether 

 it be living organised germ or dead unorganised matter, these 

 experiments do not explain or attempt to explain. 

 I Leonard W. Sedgwick 



