194 On the Real Nature Pon Oe em 
important bearing on the question of the nature of the poison of 
contagious diseases. Many such fluids are clear like water, and 
quite as transparent when examined by the unaided eye only. 
When we come to subject them to examination with the aid even of 
the highest powers yet made, although solid particles are detected, 
and sometimes in great number, we observe nothing peculiar to 
these fluids alone—nothing which would enable us to form any 
conception of the wonderful properties they possess—nothing that 
would attract the attention of the chance observer, or excite the 
interest of anyone who had not long and carefully studied the 
matter. Nevertheless, what we are able to demonstrate is of vast 
importance, and with the aid of other observations and experiments, 
we may form, I think, clear notions of the nature and origin of 
these morbid poisons, and of the manner in which they produce 
their marvellous and oftentimes disastrous effects. Much yet re- 
mains to be disclosed, but we shall soon learn more if we will but 
work and think independently, and accept the teaching of facts of 
observation and experiment, while careful to avoid being misled by 
the dogmatism of those who obstinately persist im asserting that 
all vital phenomena are to be explained by physics and chemistry, 
and try to make people believe that lvimg organisms are mere 
machines constructed by force. All truly vétal phenomena must 
necessarily be altogether out of the range of mere physical investi- 
gation. Nevertheless, to such extravagant lengths has the opposite 
view been carried of late, that it has even been seriously stated 
that he who refuses to look upon life as mere inorganic force, 
opposes investigation, and looks upon the structure of man’s 
organism as a subject unsuitable for scientific exploration. It would 
be as reasonable to assert that a man who is to be a scientific 
investigator must commence by confessing his belief in the truth of 
a conclusion which has long been proved to be false by reason and 
observation.* 
In spite of all the evidence adduced to the contrary, and not- 
withstanding the failure of all attempts to prove the vegetable 
nature of disease germs, Mr. Simon still adheres to this doctrine. 
He seems to place great reliance upon the extraordinary statements 
of Hallier, which have not been confirmed, and ought to be received 
with the greatest caution. In his Report for 1869, Mr. Simon 
makes the following remarks upon this subject :—“ Knowing that 
all contagia (as such) are distinct one from the other, and be- 
lieving that each of them has its essence in the so-called microzymes 
* The physical theory of life is, however, less popular now than it was a few 
years ago. Quite recently its strongest advocates have expressed themselves more 
cautiously than has been their custom hitherto. They have discovered that the 
“tendency of thought” is fast setting in another direction. They have, therefore, 
modified their statements without withdrawing them, and have made preparations 
for abandoning their position without acknowledging defeat. 
