4 DR. BASTIAN ON THE 



In the experiments of this kind now to be described I have had 

 recourse to the aid of a stimulating physical influence (viz. heat), 

 which has been much more sparingly resorted to by other inves- 

 tigators, as well as by myself, on previous occasions ; I have also 

 made use of certain chemical agents (viz. oxygen and liquor po- 

 tassae) under conditions as novel as they are stringent. In several 

 respects, indeed, the experiments about to be recorded differ much 

 from those hitherto made for the purpose of throwing light upon 

 the two correlated and much vexed questions, as to the conditions 

 of origin of fermentations, and as to the present occurrence or 

 non-occurrence of archebiosis . 



Whilst I have been careful to call to my aid all those conditions 

 and influences which were admissible and might, within the nar- 

 row boundaries of a strictly trustworthy experiment, be supposed 

 to favour the process of fermentation, I have also neglected no 

 precaution, however trivial, which has hitherto been insisted upon 

 as needful for the completeness of the preliminary destructive 

 process. I have stedfastly sought to destroy every trace of pre- 

 existing living matter within the glass-bounded field of experi- 

 ment, without unnecessarily deteriorating the mere organic matter. 

 With this end in view, in a large proportion of the experiments 

 the precaution has been taken, after boiling the fluids and hermeti- 

 cally sealing the vessels, to immerse them in an inverted position 

 in a can of boiling water for 5"-15". By this means the portions of 

 the retort- or flask- walls which, during the boiling over the flame, 

 are only exposed to brief contact with the boiling fluid or to steam, 

 come during the boiling in the can continuously into contact 

 with the infusion itself heated to 212° ¥. An interval of three 

 quarters of a minute must, in these cases, be allowed to elapse after 

 the sealing of the tip of the retort or flask before it is inverted and 

 plunged into the boiling water, in order that this over-heated tip 

 may not crack by coming into contact with the fluid within. This 

 accident will also be diminished in frequency by long practice, and 

 by careful sealing in such a manner as to avoid any inbending of 

 the glass. When a minute crack has occurred, it is always 

 rendered obvious, during the period that the vessel is cooling, by 

 a line of small air-beads starting therefrom. Such a vessel must 

 of course be rejected, or only kept for observation as an air-con- 

 taminated specimen. 



A few words are desirable as to the best mode of subjecting 

 the experimental fluids to any given generating temperature. 



