io8 NATURAL SCIENCE. Feb., 



This body of evidence, which might be largely amplified, is 

 sufficient to show the secure basis upon which the antitoxin theory 

 rests. It is proved that germicidal proteids exist in the blood of 

 some naturally immune animals : it is proved that, as the result of a 

 non-fatal attack of an infectious disease, the subsequent immunity, of 

 longer or shorter duration, is associated with the presence, in the 

 blood, of a substance capable at least of neutralising the specific 

 toxins of the disease in question, if not of killing the organisms 

 which cause it. Klein has suggested that there may be both a 

 chemical antidote, or true antitoxin, and a germicidal body in the 

 blood of an immunised animal, and that one or the other, or both, 

 may be present, according to the method of immunisation employed. 

 It is not yet known how or where this antitoxin is formed — what 

 tissue or organ is charged with its production, or whether it is derived 

 from the very bacteria themselves. It seems likely that there may 

 be a separate antitoxin for each specific infective disease : there is at 

 least no evidence pointing away from such a supposition. 



The discovery of antitoxic bodies in the blood is clearly one of 

 the highest moment and capable of the most important practical 

 applications. The success or failure of such practical applications 

 will go far to prove or disprove the truth of the theories upon which 

 they are based. The system of ".serum therapeutics" is, however, 

 the direct outcome of experimental facts rather than of preconceived 

 theory. Though still in its infancy, enough has already been achieved 

 in the case of diphtheria to warrant the belief that it is as valuable in 

 practice as it is sound in theory. 



The first practical step was the outcome of the observations of 

 Behringand Kitasato on the immunisation of animals against tetanus. 

 It was found that, in favourable cases, the symptoms of declared 

 tetanus in animals might be removed or alleviated by the injection of 

 antitetanic serum. Wider experience, however, soon showed that it 

 was a much easier thing to prevent the appearance of symptoms than 

 to cure them when they were once manifest. Nevertheless, in a 

 disease so fatal and so intractable as tetanus, it seemed well worth 

 while to try the effect of antitetanic serum in human cases. This 

 has now been done in a number of instances and with varying 

 success. Eight successful cases have been reported from Italy, 

 treated with serum prepared by Tizzoni and Cattani ; but most of 

 them seem to have been slight or chronic cases, the natural mortality 

 of which is not high. Roux and Vaillard have reported seven cases 

 with only two recoveries, and the results of other observers have not 

 been very encouraging. Hewlett has, however, collected 61 cases 

 treated with tetanus antitoxin, with a fatality of 36 per cent., and this 

 is a distinct improvement on the ordinary fatality of the disease, which, 

 according to Conner, is as high as 80 per cent, in cases of wound 

 infection; though less than 50 per cent, in cases of apparently spon- 

 taneous origin. Severe and acute cases seem to be less benefited by 



