218 INFLAMMATION AND SUPPURATION 



present, the staphylococcus aureus, however, occurring most 

 frequently. Pneumococci have been found alone in some cases, 

 and in a considerable number of cases following typhoid fever 

 the bacillus typhosus has been found alone. In others, again, 

 the bacillus coli communis is present. 



The affection of the periosteum or interior of the bones by 

 these organisms, which is especially common in young subjects, 

 may take place in the course of other affections produced by 

 the same organisms or in the course of infective fevers, but in a 

 great many cases the path of entrance cannot be determined. 

 In the course of this disease serious secondary infections are 

 always very liable to follow, such as small abscesses in the 

 kidneys, heart- wall, lungs, liver, etc., suppurations in serous 

 cavities, and ulcerative endocarditis ; in fact, some cases present 

 the most typical examples of extreme general staphylococcus 

 infection. The entrance of the organisms into the blood stream 

 from the lesion of the bone is especially favoured by the 

 arrangement of the veins in the bone and marrow. 



Experimental. Multiple abscesses in the bones and under the peri- 

 osteum may occur in simple intravenous injection of the pyogenic cocci 

 into the blood, and are especially liable to be formed when young 

 animals are used. These abscesses are of small size, and do not spread 

 in the same way as in the natural disease in the human subject. 



In experiments on healthy animals, however, the conditions are not 

 analogous to those of the natural disease. We must presume that in the 

 latter there is some local weakness or susceptibility which enables the 

 few organisms which have reached the part by the blood to settle and 

 multiply. Moreover, if a bone be experimentally injured, e.g. by actual 

 fracture or by stripping off the periosteum, before the organisms are 

 injected, then a much more extensive suppuration occurs at the injured 

 part. 



Erysipelas. A spreading inflammatory condition of the skin 

 may be produced by a variety of organisms, but the disease 

 in the human subject in its characteristic form is almost 

 invariably due to a streptococcus, as was shown by Fehleisen in 

 1884. He obtained pure cultures of the organism, and gave it 

 the name of streptococcus erysipelatis ; and, further, by inocu- 

 lations on the human subject as a therapeutic measure in 

 malignant disease, he was able to reproduce erysipelas. As 

 stated above, however, one after another of the supposed points 

 of difference between the streptococcus of erysipelas and that of 

 suppuration has broken down, and it is now generally held that 

 erysipelas is produced by the streptococcus pyogenes of a certain 

 degree of virulence. It must be noted, however, that erysipelas 

 passes from patient to patient as erysipelas, and purulent con- 



