Bacteria in Organic Infusions. 119 



have now placed it beyond all question of doubt or cavil that living 

 Bacteria, Torulfe, and other low forms of life will make their ap- 

 pearance and multiply within hermetically-sealed flasks (containing 

 organic infusions) which had been previously heated to 212° F., 

 even for one or two hours. This result is now so easily and surely 

 obtainable, as to make it come within the domain of natural law." 

 And in a note is added, " In a very large number of trials I have 

 never had a single failure when an infusion of turnip has been 

 employed ; and from what I have more recently seen of the effects 

 produced by the addition of a very minute fragment of cheese to such- 

 an infusion,* I fully believe that in 999 cases out of 1000, if not 

 in every case, a positive result could be obtained." Though this is 

 one of a great number of statements made by Dr. Bastian upon 

 which he bases speculations as to the prevalence of spontaneous 

 generation or archebiosis, we think it necessary to state that we 

 have not considered that (which is a question of interpretation) as 

 the point at issue, but merely the question of fact as to the aj^pear- 

 ance of Bacteria in what may be considered, according to our pre- 

 sent lights, infusions duly guarded from inoculation. The point 

 under discussion is one as to a fact in the natural history of Bac- 

 teria, in a further study of which we are occupied at the instance 

 of the Eadcliffe Trustees ; and we believe that a more precise know- 

 ledge of the life-history, life-conditions, and various forms of these 

 organisms is necessary before the hypothesis of their spontaneous 

 generation can serve as a safe guide in scientific investigation. 



The experiments recorded below were made with infusion of hay 

 and with infusion of turnip, sometimes with the addition of a few 

 fragments of pounded cheese. It is necessary at once to call at- 

 tention to three precautions which we have taken, and which we 

 think are indispensable: — 1. Eecognizing the fact that the pre- 

 sence of lumps is a possible source of error, we excluded these from 

 our infusion, either by filtration or by decantation. 2. To ensure 

 the satisfactory exposure of the whole contents of the tube to the 

 boihng temperature, we, as a rule, completely submerged our expe- 

 rimental tubes in boiling water for a period varying from five 

 minutes to half an hour. 3. The substances used in preparing the 

 infusions being necessarily of a very heterogeneous nature, we 

 always examined samples of the infusions before and after boiling, 

 at the time of closing the tubes, and were thus able to determine 

 whether any change had taken place in the visible particles con- 

 tained in the fluid after a lapse of time. 



The microscopes used by us throughout, working side by side 



with samj)les from the same infusion, were a Hartnack's Stative YIII. 



objective No. 10 a immersion, ocular 4, belonging to the anatomical 



department of the University Museum, and a large Powell and 



* See Appendix C, pp. xxxiv-xxxviii. 



VOL. X. L 



