666 
E. ROUX, L. MARTIN AND A. CHAILLOU. 
of animals that have been immunized against various infectious 
diseases. The only thing that distinguishes one from another is 
the specific action of each upon a determined virus or poison. 
The animals which receive the diphtheritic antitoxine be¬ 
come refractory to the disease in a very short time. The im¬ 
munity is established at once, but it does not last, it disappears 
within a few days or weeks, according to the potency of the 
dose of the serum that has been administered. This temporary 
immunity is very different from that which is acquired by the 
slow process that we have described. 
What action is exerted upon the toxine by the anti- 
diphtheritic serum ? Are the two substances neutralized or do 
they exist side by side ? If they are not saturated, why are the 
effects of the poison no longer manifested ? It appears as if 
the toxine must be destroyed. But a mixture which gives no 
effects in a guinea-pig will still act in a rabbit, in which it pro¬ 
duces a marked oedema of the tissues in which it is injected. 
The results will change with the mode of experimenting. We 
can only say that the anti-diphtheritic serum is not antitoxic in 
the true sense of the word ; added to the toxine, it leaves it in¬ 
tact ; injected in animals, it acts upon their cells, causing them 
to lose their sensitiveness to the poison. The proof of this is 
seen in the fact that an amount of serum which preserves an 
ordinary animal will fail to save one that has been weakened 
beforehand by injections of other microbes or microbic pro¬ 
ducts. If the antitoxine destroyed the toxine, a given amount 
would be efficacious in all guinea-pigs of a given weight. The 
natural explanation of these facts must reside in the action of 
the serum upon the cells. The lively cells of a healthy animal 
respond to the stimulation of the serum, whereas in an animal 
that appears healthy, but who has been weakened previously 
by microbic injections, these cells are unable to protect. 
The study of phagocytic reaction in diphtheria has been 
undertaken at the Pasteur Institute by Dr. Gabritchewski ; the 
results he has obtained bear out the fact that preventive serums 
are stimulant rather than truly antitoxic. 
