i iil 
NVATUR 
iu 
2 
0 
| THURSDAY, FEBRUARY 3, 1870 
| 
; THE ATMOSPHERIC-GERM THEORY 
WE have heard much during the last week or two 
concerning the presence of organic matter in the 
atmosphere, and the degree to which this is filled with 
“germs” of living things. It would have been better, 
perhaps, had it been always pointed out more distinctly 
that the two expressions were by no means uniformly 
convertible. There is unquestionably much mere organic 
débris in the atmosphere which nobody could regard as 
germs of living things. 
The transition, in the minds of many at the present 
day, however, from the idea of organic matter in the 
| atmosphere, to the identification of this with germs of 
actual animal and vegetable organisms, occurs only too 
easily. The air is supposed by them to be teeming 
| with potential living things most varied in kind. Each 
square foot of atmosphere is thought to contain repre- 
_ sentatives of innumerable varieties, which are only await- 
ing the advent of suitable conditions in order to commence 
_ their growth and development. Men talk most glibly about 
germ-theories of disease, and the share which germs take 
in the origin of epidemics, as though these were proven 
facts of science rather than, as they are at present, mere 
questionable hypotheses. And, just as these germ-theories 
concerning epidemic disease have grown out of the more 
general pansfermic doctrine, so did this doctrine itself 
grow out of the great “spontaneous generation” contro- 
versy somewhat more than a century ago. As it was with 
the derived, so was it with the original doctrine : in each 
case it was produced, not so much on account of any 
direct evidence in favour of the existence of such germs, 
but rather on account of the inherent difficulty in the 
explanation of the subject to which it referred. Pre- 
vious to the period mentioned, however, no such doc- 
trine had been started. There were, of course, the 
old pantheistic doctrines of Anaxagoras and his fol- 
lowers—the notion of the universal diffusion of an active 
principle or vots pervading all things, which was 
itself the cause and source of all the life on our globe: 
there was also the doctrine of Leibnitz, concerning 
“Monads,” as centres of force and life existing in all 
things ; but anything like the present “ panspermic” doc- 
trine was still wanting. 
The Aristotelian notions concerning the “spontaneous 
generation” of even complex living things, received a 
severe blow by the experimental demonstration of Rédi, 
in 1638, before one of the Italian academies. He showed 
that the larvee found in putrefying flesh had been deposited 
there by flies, and had not been engendered (as had been 
previously supposed) by changes taking place in the flesh 
itself. Hence a very desirable modification of their 
views was necessitated on the part of the hetero- 
genists. It was not, however, till about a century after 
this that the “spontaneous generation” doctrines were 
again prominently brought before the scientific world. 
Then, too, they appeared in a form more suited to our 
present notions. The long controversy carried on between 
Needham, the English champion of heterogeny, and the 
Abbé Spallanzani, resulted in the promulgation by the 
latter of the celebrated “panspermic” doctrine. The 
question pressing for solution was, What is the mode of 
origin of the myriads of the lowest forms of life which so 
soon teem in organic solutions? According to Needham 
many of these lowest living things had been evolved de novo 
owing to changes taking place in the organic matter of the 
infusion ; according to Spallanzani they had been ulti- 
mately derived from “ germs” which, floating everywhere 
in the atmosphere, had, in spite of all precautions, gained 
access to the solutions. Spallanzani did not pretend that 
he had seen these “germs,” their existence was a mere postu- 
lation and no other evidence of their reality was alleged than 
the occurrence of the very phenomena which their presence 
was supposed to explain. His position was interpretable 
in this way. Heseemed to think that such new evolution 
of life was impossible. If living things occurred, there- 
fore, they #zwst have originated from pre-existing germs. 
Against unchangeable convictions of this kind, occurring 
either then or now, of course no amount of experimental 
evidence would be of any avail. Spallanzani preferred to 
believe that the atmosphere carried with it everywhere 
myriads of germs of elementary organisms, or, at all 
events, sundry frincip~es préorganisés, invisible and imagi- 
nary though they might be. On this subject he says* :— 
“The infusorial animalcules undoubtedly take origin, in 
the first place, from certain princifes préorganisés, but 
these Arincipes, are they eggs, germs, or other similar cor- 
puscles ?” To which he most honestly adds :—“ If it is 
necessary to offer facts in reply to this question, I frankly 
acknowledge that we have no certain knowledge on the 
subject.” 
Bonnet was the contemporary of Spallanzani, and he 
was also the advocate of a doctrine similar inits tendency, 
though infinitely more extravagant. Bonnet’s leading 
notion of the “embditement des germes” is thus illus- 
trated in one of the earlier chapters of his work t :—“ The 
sun, a million times larger than the earth, has for an 
ultimate constituent a globule of light, of which several 
thousand millions enter at once into the eye of an animal 
twenty million times smaller than a flesh worm .... But 
reason can penetrate even further. From this globule of 
light it can see issue another universe having its sun, its 
planets, its plants, its animals, and amongst these last an 
animalcule which is to this new world what that, of which 
I have just spoken, is to the world which we inhabit.” 
Now, it would certainly be wrong to restrain any man in 
the exercise of his fancy, but it surely is deplorable when 
we find the results of such exercise—such mere figments 
of the imagination as this—warping the reasonings of 
succeeding generations when they come gravely to argue 
about questions of fact. 
Such, then, has been the origin of the “ panspermic ” 
doctrine. Its first supporters commenced with assump- 
tions, which could only be supported by the occurrence of 
the very phenomena that were the subjects in dispute, 
and to explain which the assumptions had been started. 
This was the doctrine of which M. Pasteur first attempted 
the experimental verification. How far he succeeded in 
the attempt is another question. On the part of those who 
first promulgated the “ panspermic” doctrine, there cer- 
tainly was nothing but mere fancy and hypothesis. 
* Opuscles de Physiques, animale et végétale. Pavie, 1787. 
p- 230. 
+ Considerations sur les Corps Organisées, 
Tom, I. 
Amsterdam: 1772, 
