Die Parasiten der Infectionskrankheiten. 23 
of microscopists, whose spores and germs of disease have sprouted 
luxuriantly for a while in popular reputation, but have had a 
mushroom «uration only in the annals of science. I am aware 
that the micrococcus and torula forms of fungi, alike in all, give 
no evidence of their nature and origin, and that all that can be 
said respecting those I have had under my observation is, that it 
is possible that these germs, developing luxuriantly in the bile 
and voided with the faeces, may be the source of the contagion 
which proves so fatal in the western pastures where Texas cattle 
have occupied them in advance of native herds. Whatever may 
be the bearing of these researches upon the etiology of the dis- 
ease, they have an abstract interest and value independently of 
their practical application. 
The fungus origin of zymotic diseases is now conceded by 
the highest authorities in mycological research, and the Texas 
fever is one which points with unusual clearness to this mode of 
propagation. That Texas cattle should communicate the disease 
while in a state of apparent health, and that Northern cattle dying 
from the virulence of the infection should be, as a rule, inca- 
pable of communicating it, can be readily understood on the hy- 
pothesis that a definite stage or amount of development is required 
by the organic germs of the contagion before they become capable 
of giving off the infectious spores by which it is propagated. The 
history of yellow fever shows how complete may be the immunity 
acquired by acclimation against a virulent form of contagion; and 
if the disease we have been studying were denominated „bovine 
yellow fever“, no fault could be found with the designation. It is 
now admitted that persons in apparent health may convey the 
germs of cholera Asiatica from an infected district, their excreta 
undergomg a kind of fermentation through the multiplication of 
fungus germs, rendering them highly infectious. 
According to recent researches, the different stages in the 
development of the same fungus possess very different properties 
and react very differently upon the human system. Thus the best 
authorities assert that achorion Schoenleini, which is known to 
be the cause of herpes circinatus and of favus *), as I have pro- 
*) Hierfür ist zu bemerken, dass der Pilz des Favus und seines häufig als 
Herpes eircinatus beschriebenen Vorstadiums identisch sind, dass dagegen der 
Pilz des echten Herpes tonsurans ein ganz verschiedener ist. Penicillium cru- 
