584 IMMUNITY 



ment was coming into use it was observed that if during an 

 epidemic the supply of serum failed, the mortality at once rose, 

 in two instances recorded it was doubled. It must here be re- 

 membered that from "the spread of bacteriological knowledge the 

 diagnosis of diphtheria is now much more accurate than formerly. 

 Another effect of the antitoxic treatment has been that when 

 tracheotomy is necessary the percentage of recoveries is now much 

 higher, being 73 per cent, instead of 27 per cent, in a group of 

 cases collected by the American Pediatric Society. In statistics 

 from London fever hospitals, the recoveries after tracheotomy were 

 56*4 as compared with 32 '1 per cent, previous to the introduction 

 of antitoxin. A striking result in the same hospitals brought 

 out by the statistics was a reduction of the death-rate in post- 

 scarlatinal diphtheria from 50 per cent, to between 4 per cent, 

 and 5 per cent. As the disease here occurred while the patient 

 was under observation, the treatment was nearly always begun 

 on the first day. It is a matter of prime importance that the 

 treatment should be commenced whenever the disease is recog- 

 nised clinically, and a bacteriological diagnosis should not be 

 waited for. Behring showed that in cases treated on the first and 

 second days of the disease the mortality was only 7*3 per cent., 

 and this has been generally confirmed, whilst after the fifth day 

 it was of little service to apply the treatment. In order to 

 obtain such results, it cannot be too strongly insisted on that 

 attention should be given to the dosage. In the treatment of 

 acute tetanus by the antitoxin the improvement in results has 

 not been marked, but some chronic cases have been benefited, 

 and, as already stated (p. 444), better results are obtained in 

 acute cases if intravenous injection be practised. In the case of 

 Yersin's anti-plague serum, though some benefit has appeared to 

 follow its use, this has been of quite a limited nature. With 

 regard to antivenin, Lamb showed that, if a cobra with full 

 glands bites a man, many times the minimal lethal dose are 

 probably injected. In cases of slight bite, however, benefit may 

 accrue from the use of the anti-serum. 



As has been shown above, antibacterial sera require for their 

 bactericidal action a sufficiency of complement, and as this 

 diminishes in amount when a serum is kept, the unsatisfactory 

 results with this class of sera may be due to a deficiency of 

 complement. Or it may be as Ehrlich has suggested, that the 

 complement naturally existing in human serum does not suit 

 the immune-body in the anti-serum that is, is not taken up 

 through the medium of the latter and brought into combination 

 with the bacterium. And there is still the further possibility 



