328 SCIENCE PROGRESS 



I was, perhaps, the first to use the " complement fixation test " as a quantitative 

 measure of the immunity produced by vaccine inoculations. The leading article 

 in the Lancet on my work criticised this method of measuring immunity. Since 

 the test, however, is really a mode of estimating "precipitins," which are anti- 

 substances, I fail to see why this criticism was forthcoming, and my faith in the 

 method remains unshaken. Anyhow, it was ascertained by means of this test that 

 large inoculations of the detoxicated germ substance produced much more 

 immunity than small doses of the toxic germs themselves. Moreover, clinical 

 observations corroborated the scientific findings, since the curative results of the 

 two vaccines showed that large doses of the detoxicated type were distinctly 

 superior in treatment to the small doses of the ordinary toxic variety. 



More recently I have applied the same chemical process of detoxication to a 

 series of other germs, with more or less similarly successful results. It is quite 

 obvious, however, that different germs vary very much in their chemical compo- 

 sition. 



The influenza bacillus and the meningococcus are, like the gonococcus, 

 extremely soluble in alkali ; others, however, such as tubercle bacilli, staphylococci, 

 and streptococci, etc., are very insoluble, and require the prolonged action of 

 strong alkali containing a trace of chlorine. When once dissolved, these latter 

 germs can readily be precipitated by acid like the others. The most difficult 

 germs to pass through the process of detoxication are such organisms as the 

 typhoid bacillus, Bacillus colt, and Friedlander's bacillus. These are dissolved 

 readily enough in alkali, but they are extremely difficult to precipitate by the 

 addition of acid. It seems a good rule that light germs which sediment slowly 

 are very difficult to precipitate, and vice versa ; heavy germs which sediment 

 rapidly are easy to throw out of alkaline solution by acidification. The addition of 

 sodium chloride to the acid aids the precipitation very markedly ; but, unfortu- 

 nately, as already mentioned, this tends to precipitate the toxin as well. In 

 consequence the concentration of sodium chloride which can be used is limited to 

 about 5 per cent. Alcohol aids precipitation in some cases, but it also precipitates 

 the toxin, so its use is to be avoided. 



With regard to the gonococcus, it was noted that about two-thirds of the germ- 

 substance was thrown out of the alkaline solution by acidification, and that about 

 one-third of the material (which is toxic in nature) remained in the supernatant acid 

 fluid. On the other hand, in the case of such germs as the typhoid bacillus and 

 Bacillus coli, it would appear that this proportion is reversed, since only about one- 

 third is precipitated by the acid, while two-thirds remain in colloid solution in the 

 acid supernatant fluid. Furthermore, these germs are not so readily detoxicated 

 as the gonococcus, since the final precipitate obtained after repeating the process 

 six times cannot be injected in such large doses as in the case of the latter. 



It would appear, however, that all germs can be detoxicated successfully by the 

 process in a greater or lesser degree. The only point of difference is that varia- 

 tions in the strength of the alkali are required to suit each organism. I feel 

 confident that, with further researches on detoxication on the above lines, the 

 problem of the administration of the large inoculations necessary in order to produce 

 a high degree of immunity without harmful effects will be completely solved. 



Vaccines have been employed not only for preventative, but for curative, 

 purposes. Thus small doses of the appropriate germ may be given with good 

 results in the course of a disease. In such cases, however, the amount injected 

 must be smaller than in the case of preventative inoculations, which are adminis- 

 tered during health. This necessity of giving tiny doses during an illness detracts 



