Dr. H. C. Bastian on the Origin o/" Bacteria. 385 



slightly alkaline fluids which have been merely raised to the 

 boiling-point *. 



Even M. Pasteur, however, admits that the germs of Bacteria 

 and other allied organisms are killed in slightly acid fluids which 

 have been boiled for a few minutes ; so that there is a perfect 

 unanimity of opinion (amongst those best quahfied to judge) as 

 to the destructive effects of a heat of 212° F. upon any Bacteria 

 or BLwteria-germ.s which such fluids may contain. 



Taking such a fluid, therefore, in the form of a strong filtered 

 infusion of turnip, we may place it after ebullition in a superheated 

 flask \\'ith the assurance that it contains no living organisms. 

 HaWng ascertained also by our previous experiments \dth the 

 boiled saline fluids that there is no danger of infection by Bacteria 

 from the atmosphere, we may leave the rather narrow mouth of 

 the flask open, as we did in these experiments. But when this is 

 done, the previously clear turnip-infusion invariably becomes turbid 

 in one or two days (the temperature being about 70° F.), owing to 

 the presence of mjTiads of Bacteria. 



Thus, if we take two similar flasks, one of which contains a 

 boiled " Pasteur s solution " and the other a boiled turnip-infusion, 

 and if we place them beneath the same bell-jar, it will be found 

 that the first fluid remains clear and free from Bacteria for an 

 indefinite period, whilst the second invariably becomes turbid in 

 one or two days. 



What is the explanation of these discordant resvdts ? We have 

 a right to infer that all preexisting life has been destroyed in each 

 of the fluids t; we have proved also that such fluids are not 

 usually infected by Bacteria derived from the air ; in this very 

 case, in fact, the putrescible saline fluid remains pure, although 

 the organic infusion standing by its side rapidly putrefies. We 

 can only infer, therefore, that whilst the boiled saline solution is 

 quite incapable of engendering Bacteria^, such organisms are able 

 to arise de novo m the boiled organic infusion. 



Although this inference may be legitimately draTMi from such 

 experiments as I have here referred to, fortunately it is confirmed 

 and strengthened by the labours of many investigators who have 

 worked under the influence of much more strmgeut conditions, 

 and in which closed vessels of various kinds have been employed §. 



Whilst we may therefore infer (1) that the putrefaction which 



* How unwarrantable such a conclusion appears to be, I have elsewhere 

 endeavoured to show. See ' Beginnings of Life,' 1872, vol. i. pp. 326-333, 372- 

 399. 



t [Note. Jan. 31, 1873.]— In 'The Beginnings of Life,' vol. i. p. 332, note 1, 

 I have cited facts strongly tending to show that Bacteria are killed in infusions 

 of turnip or of hay when these have been heated to a temperature'of 140° F. 

 They also seem to die at the same temperature in solutions of ammonic tartrate 

 with sodic phosphate. 



X See ' Beginnmgs of Life,' vol. ii. p. 3,5, and vol. i. p. 463. 



§ See a recent communication by Prof. Burdon Sanderson, in ' Nature,' 

 January 9th. 



Ann. cfe Mag. N. Hist. Ser. 4. Vol. xi. 25 



