1871.] The Theory of Atmospheric Germs. 157 



organisation; M. Pouchet and the heterogenists, that they 

 are far too infrequent and insufficient to account for the 

 phenomena. 



The question, " Are the organisms which have been 

 observed and described sufficient to account for the multi- 

 tudes of living forms which are met with in the course of 

 putrefaction?" is of the first importance. If so, they ought 

 to be observed upon or within the putrescible solution, 

 and their mode of multiplication should be distinctly 

 made out. It is, however, certain that this cannot be 

 established. When an organic solution is examined, prior 

 to the commencement of putrefaction, the highest powers 

 of the microscope fail to detect the ova or spores of the 

 future minute organisms. There remains, therefore, this 

 dilemma : either the germs are invisible or else the primi- 

 genetic molecules are self-formed in the fluid. We should 

 then inquire if there is anything in analogical evidence 

 which could tend to the conclusion that the germs of living 

 things are so minute that the microscope cannot detect 

 them. Dr. Beale, using the highest powers, figures 

 extremely minute masses of germinal matter which develop 

 into perfect fungi, yet which might elude very close inves- 

 tigation ; and it is far from certain that these are not the 

 indices of still more minute particles of living matter. It is 

 surely unfair to stay further investigation by asserting at 

 once that, because the germs cannot be demonstrated, there- 

 fore the inquiry is at an end, and the question is judged. 

 The heterogenists have constantly urged this : they say 

 " Show me a specimen of these creatures and I will admit 

 them ; otherwise I shall declare that they do not exist." 

 The eye alone is not the test absolute of the cause of phe- 

 nomena. Would a philosopher assert that a man could 

 safely enter a poisonous atmosphere because he could see 

 nothing wrong even with the highest aid to his visual 

 powers ? Would it be fair to conclude after the inoculation 

 of vaccine virus into an animal that no virus exists in its 

 blood because none can be detected ? Would it be fair to 

 infer that the weeds which appear in such abundance in our 

 gardens spring up spontaneously because we cannot trace 

 their seeds as they are wafted by the air ? The method 

 which Professor Tyndall has popularised has shown that the 

 apparently homogeneous atmosphere which we breathe is 

 dense with floating particles ; the minuteness of these 

 particles is extreme. It has been asserted that though many 

 filters fail to intercept them, a stratum of cotton-wool is a 

 perfectly efficient filter ; but we must not entirely accept 



