1871.] The Theory of Atmospheric Germs. 167 



exist in crystals by physical demonstration. That once in 

 a saline solution such vital organisms can grow and propa- 

 gate is no matter of doubt — it is admitted by either side. 

 Pasteur showed that a salt of ammonia and the phosphates 

 could become a perfect pabulum for torula cells. The 

 oxalates and phosphates have been shown by Hallier to be 

 excellent media for the development of fungoid fibres, 

 oidium forms, mycoderms, and fructifying organisms. The 

 whole difficulty rests, therefore, with the earliest phenomena. 



It behoves us to inquire into the teaching of the negative 

 as well as the positive results. That the proliferation of 

 forms of life under restrictive influences such as have been 

 mentioned is exceptional is taught by the results of every 

 labourer in the field. Privation of air is admitted to be 

 a most potent cause in prevention of the appearance of or- 

 ganisms: or to put it in another way, "experiments in closed 

 vessels are quite unfavourable to the demonstration of 

 heterogeny, because the natural and regular progress of the 

 phenomena is paralysed." Increment of heat is another ad- 

 verse influence, " because the destructive agent impairs with- 

 out destroying that organising force which is an essential 

 property of organic matter." These are the modes of ex- 

 pressing the facts adopted by the heterogenists; and MM. 

 Joly and Musset, by actual experiment, prove that the 

 organisms in a putrescible solution submitted to ebullition 

 " are more simple and less numerous accordingly as the 

 ebullition is prolonged." In fact, we must conclude with M. 

 Pennetier "that the phenomena of spontaneous heterogenic 

 generation, intense while their regular course is respected, 

 are nevertheless manifest, though in successively lessening 

 degrees, as causes of difficulty are increased, to finally cease 

 when the phenomena of fermentation and putrefaction are 

 themselves prevented." This as an explanation of the position 

 to which science has arrived in this question it is scarcely 

 needful to say is feeble in the extreme ; it is merely a 

 categorical expression of results which can be explained at 

 least as well by the one theory as by the other. 



From the foregoing data it appears that none of the 

 arguments adduced are sufficient to invalidate the germ 

 theory. There is a mode of putting the question which 

 must appear to many to be unfair. It is alleged that the 

 onus of proof rests entirely with the Panspermatists. It is 

 not for the heterogenists to prove that germs do not exist, 

 but for the Panspermatists to prove that they do exist. " The 

 charge of proof in science rests with those who allege a 

 fact." Surely the facts support precisely the contrary view. 



