OCCURRENCE OF CAUSATIVE AGENTS. 127 



carbuncles has been demonstrated by Garre, in an experi- 

 ment upon himself. He rubbed a staphylococcus-culture 

 into the intact skin of his left forearm. Four days later a 

 characteristic carbuncle developed, and around it several 

 isolated furuncles. The pus from all of the lesions con- 

 tained the same staphylococcus that had been employed 

 for the inoculation. This experiment renders it at the 

 same time probable that furuncles and carbuncles are 

 probably due to infection of the excretory ducts of the 

 glands of the skin, into which the pyogenic material is in 

 some way forced. Practically, furuncles are often seen to 

 develop in places subjected to pressure or friction : as, for 

 instance, by parts of the clothing. 



Panaris. In the pus from panaris staphylococci, as well 

 as streptococci, and in rare cases also the bacterium coli com- 

 mune have been found. 



Abscess and Phlegmon. These are due to staphylo- 

 cocci and streptococci, and in some cases also to Frankel's 

 pneumococci, especially in childhood and in the course of 

 genuine croupous pneumonia. In abscesses in those sick 

 with and convalescent from typhoid fever, staphylococci 

 and streptococci are found frequently, and not at all seldom 

 also typhoid-bacilli and bacterium coli. Urinary phlegmons, 

 so frequently observed in the sequence of urinary infiltra- 

 tion, are usually due to the bacterium lactis aerogenes or the 

 bacterium coli commune, which play the most important role 

 in the suppurative processes of the genito-urinary apparatus. 



So-called cold abscesses are generally found to be sterile. 

 They may be considered as the product of tubercle-bacilli, 

 and actually it has frequently been possible in experiments 

 on animals to induce tuberculosis with the pus from such 

 abscesses. Microscopically, however, it has been possible, 

 only in the rarest of instances, to demonstrate in the pus 

 the tubercle-bacilli that are present in small number. Also, 

 in the larger, nontuberculous abscesses bacteria are some- 

 times not found at the center of the area of suppuration, 

 and the pus, therefore, appears sterile. It is only necessary 

 in such cases to examine material from the periphery, the 

 so-called abscess-membrane, in order to find the pyogenic 

 agents without difficulty. 



Gas-abscesses, like ordinary abscesses, do not possess 

 a uniform etiology. From them there have thus far been 

 cultivated : (i) The bacterium coli commune and the bac- 



