IL. 
CHANNELS OF INFECTION. 
WE have abundant evidence that susceptible animals may be in- 
fected by the injection of various pathogenic bacteria beneath the 
skin, and'accidental infection through an open wound or abrasion 
of the skin is the common mode of infection in tetanus, erysipelas, 
hospital gangrene, and the “ traumatic infectious diseases” generally. 
Other infectious diseases, like anthrax and glanders, are frequently 
transmitted in the same way. We have also satisfactory evidence 
that tuberculosis may be transmitted to man by the accidental inocu- 
lation of an open wound; and in view of the fact that susceptible 
animals are readily infected in this way, it would be strange if it 
were otherwise. 
The question whether infection may occur through the unbroken 
skin has been studied by several bacteriologists and an affirmative 
result obtained. Thus Schimmelbusch produced pustules upon the 
thigh in two young persons suffering from pyzemia by rubbing upon 
the surface a pure culture of Staphylococcus pyogenes aureus which 
he had obtained from the pus of a furuncle. The same author aiso 
succeeded in infecting rabbits and guinea-pigs with anthrax, and 
rabbits with rabbit septicemia, by rubbing pure cultures upon 
the uninjured skin. Similar results had previously been reported 
by Roth, who also showed that infection might occur through 
the uninjured mucous membrane of the nose. Machnoff also suc- 
ceeded in infecting guinea-pigs with anthrax through the unin- 
jured skin of the back, and, as a result of subsequent microscop 
ical examination of stained sections, arrived at the conclusion that 
the principal channel through which infection was accomplished was 
the hair follicles. Braunschweig, in a series of experiments in which 
he introduced various pathogenic bacteria into the conjunctival sac 
of mice, rabbits, and guinea-pigs, obtained a negative result with the 
anthrax bacillus, the bacillus of mouse septicaemia, the bacillus of 
chicken cholera, and Micrococcus tetragenus; but the bacillus ob- 
tained by Ribbert from the intestinal diphtheria of rabbits gave a 
positive result in five mice, two guinea-pigs, and a rabbit. 
