1895.] on the Antitoxic Serum Treatment of Diphtheria. 437 



acquired. Upon these various theories is based the rationale of the 

 antitoxic serum treatment of diphtheria. Ferran claims to have been 

 the first to obtain such a condition of immunity against diphtheria in 

 animals ; shortly afterwards, Fraenkel in Germany obtained similar 

 results. Seeing that this immunity depends upon an alteration in 

 the composition of the serum, should it not be possible, argued Pro- 

 fessor Behring, to take the serum of an immunised animal and transfer 

 it to a patient suffering from diphtheria, so as to help the tissues 

 and cells of the patient to cope with the toxic products of the diph- 

 theria bacillus during the earlier stages of the disease, inducing, as 

 it were, a kind of artificial immunity to help the patient over the 

 acute period of the attack when the poisons, though most virulent, 

 are most unstable, and when the tissues have not yet become accli- 

 matised to the presence of the toxic products of the bacillus; when, 

 in fact, they are paralysed and are able to do little to protect them- 

 selves. Behring so followed up this idea, that he was able to initiate 

 a system of treatment which promises to revolutionise our therapeutic 

 methods in the treatment of certain specific infective diseases. 



Working on the fact that an animal might be rendered more and 

 more insusceptible to the action of the toxic products of bacteria, 

 Behring found that he might proceed in either of two ways. He 

 might make an artificial wound with a needle, and introduce weakened 

 bacilli into the animal, the weakened bacilli then growing but feebly 

 and producing a modified toxine. After the effects of the first dose 

 had passed off, he was enabled to increase the dose and to use more 

 active bacilli, injecting them first into the tissues and eventually 

 directly into the circulation, with the result that enormous doses of 

 virulent diphtheria bacilli might ultimately be introduced without 

 giving rise to more local swelling or general febrile disturbance 

 than was first noticed when the small dose of modified bacilli was 

 introduced. Such a method as this, however, was attended with con- 

 siderable drawbacks, as it was almost impossible to gauge, at all 

 accurately, the number and strength of the bacilli. Not so, however, 

 with the products of the micro-organisms the activity of which could, 

 of course, be more accurately measured, and the dose more exactly 

 graduated. The bacilli might multiply and continue their action on 

 the tissues, but the poisons when injected alone would not alter in 

 quantity or activity. As may be readily imagined, the fluid con- 

 stituents of the blood can only contain those substances that are 

 introduced into it from without, either through the vital activity of 

 the cells of the body, the products of which must be thrown into this 

 fluid before they can be excreted, or through artificial injection. The 

 antitoxic substances, then, found in the blood of an immunised animal, 

 must in the case of natural immunity following an attack of diph- 

 theria be the result of the activity of the tissue cells, especially of 

 the connective tissue and white blood cell groups which have been 

 " stimulated " by the toxines introduced from without, from the false 

 membrane in the throat. Where it is desired to produce an artificial 

 Vol. XIV. (No. 89.) 2 h 



