i6z The Theory of Atmospheric Germs. [April, 



employed have varied in different experiments from boiling 

 for periods ranging from a few minutes to six hours 

 (Pouchet, Mantegazza, Child, Bastian) to 153 C, or 

 307*4° F. (Bastian). The means of excluding possible 

 vitality subsequently have been passing the air through a 

 tube raised to a red or white heat (Pouchet, Wyman, and 

 others), or through a tube containing strong sulphuric acid 

 (Pouchet, Joly, Musset), or supplying only oxygen (Pouchet, 

 Child, Mantegazza), or artificial air (Pouchet, Child), or by 

 preserving the boiled putrescible fluid in vacuo (Pouchet, 

 Bastian). In all these cases organisms have been described 

 as resulting. In these experiments it. would appear that the 

 conditions would be fulfilled with the least liability to 

 objection in the cases wherein the solutions were exposed to 

 very high temperatures in vacuo. M. Pouchet filled a flask 

 with a decoction of malt which had boiled for six hours, and 

 hermetically sealed it. After six days a deposit, apparently 

 of yeast, took place in the flask ; on the seventh day the 

 external temperature having been suddenly raised the flask 

 burst with a loud report. There had been fermentation, and 

 the microscope disclosed that yeast corpuscles had been 

 formed. Dr. Bastian has also performed analogous experi- 

 ments with great care. In his first series, the fluids were 

 boiled in small flasks for ten to twenty minutes, and then by 

 means of the blowpipe hermetically sealed ; after periods 

 varying in the different experiments from five to thirty-nine 

 days, the flasks were opened, and the contents were 

 examined with the result of the discovery of many lowly- 

 endowed organisms. Living bodies were also found when 

 solutions of tartrate and phosphate of soda and some other 

 saline solutions were in like manner made the subject of 

 experiment. It has been supposed that these observations 

 are very antagonistic to the germ theory, and lend colour to 

 the views of heterogenists. In briefly considering this con- 

 clusion we may divide the arguments into two classes, the 

 first being derived from the evidence of the supposed destruc- 

 tive influence of high temperatures on living matter, the 

 second from the supposed impossibility of the pre-existence 

 of germs in the fluid employed. It must be recollected that 

 by the argumentation in favour of heterogeny the method of 

 exclusion is employed, and this requires the most prolonged 

 and patient employment before its conclusions can be said 

 to approach finality. Furthermore, its upholders must be 

 prepared to substitute for the explanation of phenomena 

 which may be derived from any other theory another which 

 shall be more satisfactory. 



