86 



NATURE 



[Nov. 29, 1877 



must be learnt by the application of the various methods 

 of visual observation at our disposal, it possesses mole- 

 cular structure peculiar to itself. We are certain of this, 

 because the chemical processes of which life is made up 

 are peculiar, that is, such as occur only in connection 

 with living material. Even the simplest instance that we 

 can mention, that of the elevation of dead albumin into 

 living (a process which in the case now before us must 

 represent the very earliest step in the climax of develop- 

 ment) is at the present moment beyond the reach of 

 investigation ; for as yet we are only beginning to know 

 something about the constitution of non-living proteids. 

 But this want of knowledge of the nature of the ditference 

 between living and non-living material in no wise impairs 

 the conviction which exists in our minds that the 

 difference is one of molecular structure. 



The sum of the preceding paragraphs may be stated in 

 few words. Wherever those chemical processes go on, 

 which we collectively designate as life, we are in the habit 

 of assuming the existence of anatomical structure. The 

 two things, however, although concomitant, are not the 

 same ; for while anatomical structure cannot come into 

 existence without the simultaneous or antecedent existence 

 of the kind of molecular structure which is peculiar to 

 living material, the proof is at present wanting that the 

 vital molecular structure may not precede the anatomical. 

 At the same time it must be carefully borne in mind that 

 there is no evidence of the contrary. It is sufficient for 

 my purpose to have shown that the existence of organised 

 particles endowed with anatomical structure in the 

 "atmospheric dust" has not been proved. I do not 

 dispute its probability. 



Before leaving this subject I may be permitted to add a 

 word as to the bearing of this discussion on a question 

 which, to myself, is of special interest — that of contagium 

 vivum. According to the view which these words are 

 understood to express, the morbific material by which a 

 contagious disease is communicated from a diseased to a 

 healthy person consists of minute organisms, called 

 " disease-germs." In order that any particle may be 

 rightly termed a disease- germ 'two things must be proved 

 concerning it, viz., first, that it is a living organism ; 

 secondly, that if it finds its way into the body of a healthy 

 human being, or of an animal it will produce the disease 

 of which it is the germ. Now there is only one disease 

 affecting the higher animals in respect of which anything 

 of this kind has been proved, and that is splenic fever of 

 cattle. In other words, there is but one case in which the 

 existence of a disease-germ has been established. 



Comparing such a germ with the germinal particles we 

 have been discussing, we see that there is but little 

 analogy between them, for, first, the latter are not known 

 to be organised ; secondly, they have no power of pro- 

 ducing disease ; for it has been found by experiment that 

 ordinary Bacteria may be introduced into the circulating 

 blood of healthy animals in considerable quantities with- 

 out producing any disturbance of health. So long as we 

 ourselves are healthy, we have no reason to apprehend 

 any danger from the morbific action of atmospheric dust, 

 except in so far as it can be shown to have derived 

 infectiveness from some particular source of miasma or 

 contagium. 



I now proceed to the second part of my communica- 

 tion, which relates to Prof. Tyndall's serious, but most 

 courteously-expressed, criticisms of my experiments on 

 spontaneous generation/ 



' The expressions referred to are the following: — " I have worked with 

 infusions of precisely the same specific giavity as tho^e employed by Dr. 

 Bastian. This I was especially lareful to do in relaiion to the experiments 

 .described and vouchi d for, 1 tear incautiously, by Dr. Burdon-Sanderson, 

 in vol. vii. p. 180 of Natire. It will there be seen that though failure 

 attended some of his efforts, Dr. Bastian did satisty Dr. Sander.-on that in 

 boiled and hermetically tea'ed flasks Bacteria sometimes appear in swarms. 

 Wuh purely liquid infusions I have vainly sought to reproduce the evidence 

 which convinced Dr Sar.dtrson I am therefore compelled to con- 

 clude that Dr. Sandtrson has lent the authority of his name to results whose 

 antecedents he bad not suflEciently examintd." Phil. Trans., vol, clxvi. 



The fact that Dr. Tyndall blames me for incautiously 

 vouching for is, "that in boiled and hermetically-sealed 

 flasks Bacteria sometimes appear in swarms." From 

 multiplied experiments he concludes that this is not true, 

 and infers that I who vouched for it was incautious. The 

 paper referred to was one in which I, as a bystander, gave 

 an account of certain experiments which Dr. Bastian 

 performed in my presence. So far as relates to the fact 

 above quoted, these experiments were, to my mind, abso- 

 lutely conclusive ; but inasmuch as I was unable to admit 

 with Dr. Bastian that they afforded any proof of sponta- 

 neous generation, I followed them as soon as practicable 

 by a series of experiments (Nature, vol. viii. p. 141) 

 (the only ones which I myself ever made on this subject), 

 in which I tested the influence of two new conditions, 

 viz., of prolonged exposure to the temperature of ebul- 

 lition, and of exposure for short periods to temperatures 

 above that of ebullition at ordinary pressure. The ex- 

 periments accordingly consisted of two series, in the first 

 of which a number of retorts or flasks charged with the 

 turnip-cheese liquid, i.e. with neutralised infusion of turnip 

 of the specific gravity 10 17, to which a pinch of pounded 

 cheese had been added, and sealed hermetically while 

 boiling, were, after they had been so prepared, subjected 

 to the temperature of ebullition for longer or shorter 

 periods. In the second series the period of ebullition 

 was the same in all cases, but the temperature was varied 

 by varying the pressure at which ebullition took place. 



The conclusion arrived at, as expressed in the final 

 paragraph of the paper, was, that in the case of the 

 turnip-cheese liquid, the proneness of the liquid to produce 

 Bacteria can be diminished either by increasing the tem- 

 perature employed to sterilise it, or if the ordinary tem- 

 perature of ebullition be used, by prolonging its duration. 



I did not think it necessary after 1873 to occupy myself 

 further with the subject for two reasons, first, that I had 

 accomplished my object, which was to show that as a 

 ground for believing in spontaneous generation the turnip- 

 cheese experiment was a failure ; but secondly, and 

 principally, because in the meantinie the subject had been 

 taken up by the most competent living observers, who 

 had in every particular confirmed the accuracy of my 

 results. I conclude this paper by referring shortly to 

 some of these researches. 



The first was made by P. Samuelson under the direc- 

 tion of Prof. Pfliigeri in 1873. Its purpose was to ascer- 

 tain whether it is true that certain hquids can be boiled 

 for ten minutes without being sterilized, and secondly, to 

 determine the influence of prolonged periods of exposure. 

 The flasks employed were charged with the neutral 

 turnip-cheese liquid, and sealed while boiling in the way 

 already described. Some were subjected to the tem- 

 perature of ebullition for ten minutes, the rest for 

 an hour, the result being that whereas those heated 

 for the longer periods remained without exception barren, 

 an exposure of only ten minutes was followed, in the 

 majority of cases, by an abundant development of 

 Bacteria? At about the same period a similar series of 

 experiments was made under the direction of Prof. Hoppe- 

 Seyler at Strasburg. The results were essentially the 

 same. 2 



p. 57. In the abstract of a lecture delivered at the Royal Institution, 

 JaiiTiiary 21, 1876, similar words occur, as aUo in a letter to Nature, dated 

 Febiuary 27, 1876, in which Dr. Tynoall, after rem.rking that the experi- 

 ments ot Dr. Bascian, witnessed by me, wtre too scanty and too litt'e in 

 harmony with each other to bear an inference, suggests that 1 should repeat 

 them. . , 



^ " tJeber Abiogenesis," von Paul Samuelson aus Konigsberg, Pfliiger s 

 Archiv, vol. viii. p. 277. The paper is designated as a repon of experiments 

 made " im Auftrag und unter der Leitung des Geh.-Kath Prof Pfiuger." I 

 refer in the text only to those experiment- which were virtually repetitions of 

 my own. The research actually extended o>rer awider field. 



2 " Als Re uliat dieser Versuchsreihe, ergab tich eine massenhafte Ent- 

 wickelurg von Bacterien in den meisten nur 10 Minuten lang gekochten 

 Flussikeitsmengen nach 3-4 Tagen " {loc. cit. p. I'^i). '■ 



3 " I eber die Abiogenesis Huizioga's," von Felix Putzeys aus Luttich 

 (aus dem chemisch-physiologischen Laboratorium des Herrn Prof. Hoppe- 

 Seyler). Pfliiger's Jirchiv, vol. ix. p. 391. In a note appended by Prof 

 Koppe-Seyler to this paper he states that he has recommended its publica- 



