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SCIENCE PROGRESS 



(2) Inoculation during the positive phase ; in this case an 

 indefinite rise in the resistance of the blood should be theoreti- 

 cally produced. This is, unfortunately, not the case in practice, 

 and whereas a cumulative action in the direction of the negative 

 phase is only too readily achieved, it is generally found 



Fig. 2. — Re-inoculation during the Negative Phase. 



impossible to produce a cumulative action in the direction of 

 the positive phase (fig. 3). 



(3) If the subsequent inoculations take place as the effect of 

 the previous inoculation is passing off, the next inoculation 

 may act as an independent event, and this is the ordinary 



Fig. 3. — Ideal Inoculation. 



result achieved when animals are allowed to recover completely 

 between the successive inoculations (fig. 4). 



The practical import of these experiments will be readily 

 understood. If inoculation is resorted to in a haphazard 

 manner, it is possible that each dose will be given during 

 a negative phase, and the patient's resistance driven down 



