OPSONIC INDEX AND VACCINE THERAPY 339 



were carried out without any control of serum reactions in the 

 patient and with comparatively large doses. 



The danger to be carefully avoided, therefore, is a too rapid 

 succession of inoculations and too large a dosage, since both of these 

 procedures may be followed by cumulation of the "ebb tide of im- 

 munity," and great harm may result. On the other hand, if the 

 treatment is so spaced and measured that the successive inoculations 

 are given just before the positive phase has ended in other words, 

 just before the apex of the curve is reached a moderate negative 

 phase may be then followed by a second positive phase still higher 

 than the first, and corresponding improvement will result. It is even 

 possible to occasionally obtain a summation or cumulation of the 

 positive phase in which the negative phase will be entirely sup- 

 pressed. This is illustrated in the following curve, in the case of 

 the first and second inoculation indicated on the chart. This case, 

 too, was a staphylococcus infection occurring in a laboratory at- 

 tendant : 



STAPHYLO- 

 OPSONIC 20, 



'6&Z8&X3/ I 



IS l6l7t8'9&ZI 



STAPHYLOCOCCUS INDEX AS DETERMINED BY WRIGHT IN A CASE OF ACNE TREATED 



WITH STAPHYLOCOCCUS VACCINES. 



Note summation of positive phase after third injection. (After A. E. Wright, 

 "Studies on Immunity," p. 348.) 



Such a summation of positive phase, though of course the ideal 

 to be aimed at, cannot be produced with regularity, however carefully 

 we may attempt to control the treatment. It is worth mentioning, 

 moreover, a fact which should become evident from the preceding 

 and is too often overlooked, that a summation of the negative phase 

 can certainly be attained by the frequent repetition of larger doses. 

 This is practiced not infrequently in the false hope of hastening the 

 acquisition of immunity, and does harm more often than good. 



Ordinarily the opsonic index when raised to a level considerably 

 above normal will gradually recede to the normal or even to a sub- 



