ANTITUBERCULAR SERUM. 235 



largely practised on the Continent, and ought to be more 

 widely applied. 



Immunisation against the Tubercle Bacillus : Anti- 

 tubercular Serum. Tuberculosis differs from other diseases 

 against which animals can be immunised in that there is no 

 evidence that one attack protects against a second. Further, 

 we have no means of obtaining truly attenuated tubercle 

 bacilli. Many attempts at immunisation have, however, 

 been made. It has been thought by some that the tubercle 

 bacilli from so-called scrofulous glands are less virulent than 

 those say from phthisis, but apparently here sufficient atten- 

 tion has not been paid to the difference of the numbers of 

 bacilli injected in each case, and this appears to be a very 

 important point. Experiments have also been brought 

 forward which appear to show that the injection of bacilli 

 from avian tuberculosis could protect the dog against 

 bacilli derived from man. But these are not yet conclusive. 

 Further, many attempts have been made at immunisation 

 against the tubercle bacillus by the employment of its toxic 

 products. The most successful have been those of Mara- 

 gliano. We have seen that this author distinguishes between 

 the toxic bodies contained in the bodies of the bacilli 

 (which withstand, unchanged, a temperature of 100 C.) and 

 those secreted into the culture fluid (which are destroyed 

 by heat). The substance used by him for immunising his 

 animals consists of three parts of the former and one of 

 the latter. Commencing with 2 mgrm. of the mixture he 

 increases the dose by i mgrm. daily, till a dose of 40 to 50 

 mgrm. is reached. This latter quantity is injected daily for 

 six months, by which time a high degree of immunity 

 has been reached. The animals employed are the dog, the 

 ass, the horse. The serum obtained from these is capable 

 of protecting healthy animals against an otherwise fatal dose 

 of tuberculin. Further, a relatively much larger dose of the 

 serum will completely prevent tuberculin from causing its 

 specific reaction in tubercular guinea-pigs. Maragliano does 

 not appear to have studied the effects of this serum on 

 tubercular animals, but it has been tried in a great number 



