PRACTICAL APPLICATIONS 361 



opsonic value. But probably phagocytosis is of the main value 

 in the struggle against the streptococcus in the body. The 

 organisms are very readily taken up by the leucocytes in presence 

 of serum, and are frequently seen inside the pus cells in suppura- 

 tive diseases. In general the opsonic index may be taken as a 

 fair index of the degree of immunity, since it is usually low during 

 the course of the infection and rises as cure is brought about. 

 This has been already shown in the case of erysipelas : the index 

 returns to normal in one to three days after the rise, indicating 

 that the immunity in this case is but transient (see Fig. 63). This 

 is of interest in view of the frequency with which this disease is 

 recurrent. I have seen a case in which attacks occurred every 

 three weeks for a year. But the solid immunity conferred by 

 vaccination and the use of massive cultures is more lasting, due 

 probably to the formation of immune bodies and thermostable 

 opsonins. 



Local immunity probably also plays a part of great importance 

 in streptococcic infections, as shown by the fact that the ery- 

 sipelatous lesion usually spreads at one margin and heals at 

 another simultaneously. Yet even here the spread may be due to 

 failure of access of the blood to the bacteria. This is suggested 

 by the frequent success of the local use of iodine and other 

 rubefacients in arresting its spread. A similar effect may some- 

 times be seen in chronic cases by the use of citrates or one or 

 other of the means suggested by Wright for lowering the coagu- 

 lability of the blood. A case in which the disease had been 

 present for five weeks recovered in two days when treated in 

 this way. 



Treatment. Protective treatment is not employed. It is, how- 

 ever, interesting to note a fact pointed out by Sir James Paget 

 many years ago. Pathologists are as a rule more or less immune 

 to septic infections, and these comparatively rarely occur in those 

 who are in the daily habit of performing post-mortem examina- 

 tions. The attack which proved so nearly fatal to him occurred 

 after a long absence from the post-mortem room. Probably most 

 pathologists are vaccinated against the disease. 



The curative treatment (apart, of course, from that of the 

 local lesion, if any, and the use of general toxic and sustaining 

 measures) resolves itself into the question whether a serum or 

 vaccine should be used. This question cannot be definitely 

 settled at the present time, and the recommendations which are 



