Extra-Microscopic Organisms, 
By STANFORD E. CHAILLfi, M. D., 
Professor Physiology and Pathological Anatomy, Medical Department TJniv. La. 
Those opposed to the germ-theory of disease, and especially 
to the application of this theory to yellow fever, abuse no ar- 
gument so frequently and so satisfactorily to themselves as the 
one implied in their triumphant assertion that no such germ is 
demonstrable by the microscope : and they illogically neglect 
to contrast this negative argument with its equally unsatisfac- 
tory alternative, which is that the microscope, as well as 
chemistry, and all the appliances of physics, have also failed to 
demonstrate that the poison of yellow fever is either an inor- 
ganic, or a dead organic something. Now, the poison must be 
one of these three things, and in addition to other arguments, 
urged in the October number of this journal, in proof that, of 
the three possible hypotheses as to the nature of the poison, 
the germ-hypotheses was now the most rational, it will be well to 
understand what reasons there are, from an exclusively micro- 
chemical standpoint, for the belief that there may be living 
organisms very much more minute than the microscope can 
disclose. Confidence is felt that these reasons suffice to prove 
that a belief in the existence of living organisms invisible to 
the highest powers, attained or attainable by the microscope, 
is just as logical as is the universal belief in extra-microscopic 
atoms and molecules. 
Living protoplasm is composed of atoms and molecules, and 
the chemical constituents of protoplasm are 
well known ; hence, if the size of atoms and molecules, and if 
the least number of these indispensable to form an independent 
living organism, were known, it would be possible to determine 
how small may be the minutest organism. While science is 
unprepared to answer with any precision such question, it, 
none the less, has reached, through reasonable hypotheses, ap- 
proximative conclusions, which give no countenance to the 
common incredulity and ridicule respecting the possible 
minuteness of disease-germs, and which deserve to be better 
known. 
Since Sir Wm. Thompson’s effort to determine the probable “ size of atoms ” (Nature, March 31st, 1870), numerous oilier 
researches have been made on the subject, all tending to prove 
the almost inconceivable minuteness of atoms and molecules. 
The results of these researches, so far as they concern the pre- 
sent subject, have been instructively summarized by one of the 
highest authorities in this matter, namely, by H. C. Sorby, F. 
R. S., etc., in his anniversary address, as President of the Royal 
Microscopical Society, on the “ Relation between the limits of 
the powers of the microscope, and the ultimate molecules of 
matter.” (Nature, February 24th, 187C.) 
Prof. Sorby teaches that “the theoretical limit of distinct 
visibility ” is part of an inch, and that the perfected 
microscope of the present day has practically reached this limit, 
(some claim that even 10(vooo of an inch has been reached), so 
that no further improvement in this direction can be hoped for. 
Properly emphasizing the fact, that all calculations, respecting 
the size of atoms and molecules are, within certain limits, hypo- 
thetical, he none the less says : “ we must conclude that in the 
length of go),,,,,, of an inch, (the smallest interval that could 
be distinctly seen with the microscope) there would be about 
2000 molecules of liquid water lying end to end, or about 520 of 
albumen. Hence, in order to see the ultimate constitution of 
organic bodies, it would be necessary to use a magnifying power 
of from 500 to 2000 times greater than those we now possess. 
These, however, for reasons already given would be of no use, 
unless the waves of light were some part of the length 
they are, and our eyes and instruments correspondingly perfect. 
It will thus be seen that, even with our highest and best 
powers, we are about as far from seeing the ultimate structure 
of organic bodies, as the naked eye is from seeing the smallest 
objects which our microscopes now reveal to us. As an illustra- 
tion, I have calculated that, with our highest powers we are as 
far from seeing the ultimate molecules of organic substances, 
as we should be from seeing the conteuts of a newspaper with 
the naked eye at the distance of a third of a mile j the larger 
and smaller types corresponding to the larger and smaller mole- 
cules of the organic and inorganic constituents.” Farther, 
“ calculating then, from the various data given above [omitted 
in these citations], we may conclude that a spherical particle one-tenth the diameter of the smallest speck that could be clearly 
defined with our best and highest powers might nevertheless 
contain no less than one million structural molecules.” Finally, 
Prof. Sorby says: “ For the sake of argument, I assume that 
gemmules [a term used in Darwin’s theory of paugeuesis], on 
an average contain one million structural molecules of albumen, 
and molecularly combined water. Variations in number, com- 
position and arrangement would then admit of an almost infinite 
variety of character. On this supposition, it would require a 
thousand gammules to be massed together into a sphere, in or- 
der to form a speck just distinctly visible with our highest and 
best magnifying powers.” 
Those who have been students of the phenomena dependent 
on the so-called “ infinite divisibility of matter,” and who are 
at the same time familiar with such considerations as the 
above, are surely pardonable for condemning, as an ignorant 
prejudice, the view that there canuot be any living organisms 
too minute for disclosure by the microscope; and, also, for 
condemning, as lacking in true scientific spirit, those who, ob- 
jecting to the germ-theory, neglect to state whether the same, 
and even greater objections, do not hold equally good against 
any other conceivable theory. 
While long convinced that the germ-theory of yellow fever 
rests on firmer ground than any other theory, I none the less 
have always entertained and expressed no present hope of the 
microscopic demonstration of this supposed germ. For, 
among other reasons, there has seemed to me to be little reason 
to hope, that the less numerous and less experienced micro- 
scopic experts engaged in researches on yellow lever—a dis- 
ease which presents comparatively most unfavorable oppor- 
tunities for study—would be likely to attain success, prior to 
the attainment of success in such diseases as small-pox, 
measles, scarlatina and typhoid fever, diseases which there are, 
perhaps, equally good reasons for believing to be germ dis- 
eases, and which so occur that more numerous and experienced 
experts have comparatively the most favorable opportunities 
for their study. 
It may be well to add, that preceding facts and views consti- 
tute an addendum to my article in the October number of this 
journal, rather than an independent article.