II. 



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 tvound 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 pyaemia 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 also 

 succeeded in infecting rabbits and guinea-pigs with anthrax, and 

 rabbits with rabbit septicaemia, 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. 



