1889.1 Etiological Classification of Diseases. 963 
ulative parasites," yet one is ^rprised and almost shocked to see 
that an observer generally so logical as Hueppe, and one for 
whom I have the greatest admiration and respect, should, in a late 
article upon the " Etiologie der Cholera Asiatica " {Berliner 
Klinische Wochenschrift, No. 9, 1890) speak of this disease, 
of which he describes the cause to be a " faculative parasite," in 
the following absurd, illogical, and most decidedly contradictory 
manner, when he says, " Die Cholera asiatica ist wirklich eine 
miasmatisch-contagions Krattkheit,'' — Cholera Asiatica is truly a 
miasmatic-contagious disease. A " miasmatic-contagion " is 
an unsupposable thing. A disease of faculative-parasitic origin 
cannot be contagious in any logical sense. The parasite finds 
its primary focus of development invariably outside of any ani- 
mal organism, or it could not be faculative; and hence cannot be 
contagious. When will this absurdity be driven out of the 
minds of otherwise close observers and logical thinkers ? A 
person affected with intermittent fever is neither dangerous to 
others, nor can such an individual infect new localities,— at least 
neither of these phenomena has ever been observed in the his- 
tory of such diseases. 
Invasion or Mixed Infection. 
The time has certainly come in connection with micro-organ- 
ismal-etiological research where most exact attention must 
be given to the pathological differentiation of germs which are 
not in any direct way connected specifically with the etiology of 
a given disease, and yet may be the cause of secondary or com- 
plicating lesions. Although I have not as yet published anything 
in detail upon this subject, still it has called for a large amount of 
very exact study and much experimentation. The one question 
which has been entirely overlooked is, that if an investigator 
desires to decide upon the specific infectious quality of a given 
germ when he finds it as a complicating phenomenon in a given 
disease caused by a well-known micro-organism, he must ma*ke 
his tests in that species of animals in which he found it, and not in 
any others. It must be understood that by infection we can only 
