108 PHYSIOLOGY OF THE BACTERIA. 
In truth, the cutaneous surfaces are penetrated 
with difficulty by germs, although the hairs upon 
the surface of the body serve to collect them. 
The short hairs in the nares prevent, to some ex- 
tent, the atmospheric germs from penetrating into 
the bronchi, but this protection is not sufficient ; 
and, notwithstanding the mucus of the nasal fossze 
and of the pharynx, they may be found in the al- 
veoli of the lungs, if we may believe Rindfleisch 
and Eberth. Do the bacteria pass into the blood ? 
They may be transported in food and drink into 
the alimentary canal, where an elevated tempera- 
ture, the presence of saliva, etc., favor their de- 
velopment. On the other hand, the acid secretions 
of the stomach, the bile, and the pancreatic juice 
moderate, if they do not prevent, the multiplica- 
tion of these organisms. 
The presence of bacteria in normal blood and 
urine, or their occasional entrance into these fluids, 
are important questions, which have induced many 
contradictory researches, but which are not yet 
definitely settled. 
1 “Tf there is any organism in the blood of yellow-fever demon- 
strable by the highest powers of the microscope as at present perfected, 
the photo-micrographs taken in Havana should show it. No such organ- 
ism is shown in any preparation photographed immediately after collection. But 
in certain specimens kept under observation in culture cells, hyphomy- 
cetous fungi and spherical bacteria made their appearance after an inter- 
val of from one to seven days. The appearance of these organisms was, 
however, exceptional; and in several specimens taken from the same 
individual at the same time, it occurred that in one or two a certain fun- 
gus made its appearance, and in others it did not. This fact shows that 
the method employed cannot be depended upon for the exclusion of atmos- 
pheric germs, but does not affect the value of the result in the consider- 
able number of instances in which no development of organisms occurred 
