354 BACTEEIOLOGY OF THE EYE 



Method of preparing the solutions : 



One c.cni. of the tuberculin as sent out contains 10 milligrammes of the solid 

 substance. 



Solution I. 0'02 c.cm. of the original solution + 10 c.cm. glycerine ; 

 ,, II. 0-2 c.cm. ,, + 10 c.cm. ,, 



,, III. I'O c.cm. ,, ,, + 10 c.cm. ,, 



The tuberculin content of the solutions refers to the solid substance. 

 Perfectly clear and fresh solutions should alone be used. Solutions which are 

 older than fourteen days are cloudy and no longer efficient. 



Von Hippel and many other ophthalmologists state that, following 

 this plan, a cure can generally be arrived at, and that it can be done 

 without any risk of damage. The good results which have been recorded 

 by different authors are so numerous that many see no necessity to 

 control the treatment by complicated bacteriological methods. 



Such an extension of the treatment is strongly recommended by 

 Wright, the introducer of the ' opsonin theory,' and by many English 

 practitioners. They insist that continued tests should be made to see 

 whether the tuberculin has raised the opsonic power of the blood - 

 serum of the patient, or has maintained it at a high level. 



On account of the interest which Wright's teaching has aroused, 

 and the increasing attention which it is receiving, I will shortly give 

 the principles underlying it. 



The tuberculin is injected with the intention of producing an increased reaction in 

 the blood, 1 and a curative effect in the diseased focus. Wright attempted to 

 influence local infections of varying origin by introducing the dead cause of the 

 inflammation into the blood- stream, and thus induce the formation of antibodies, 

 especially to cause an increase in the phagocytic action or ' opsonic power. ' The 

 diseased organ, which cannot form antibodies for itself, is thus assisted, and healing 

 is promoted. It is an active bactericidal immunization with dead bacteria such as 

 has already been discussed in reference to pneumococcal serum treatment, which 

 obtains in those infections where no antitoxic serum treatment (as is possible in 

 diphtheria) can be carried out. 



Wright describes methods by which the phagocytic power of the body, and its 

 variation when tuberculin or dead cultures vaccines are injected, can be measured 

 and controlled. 



By ' opsonin ' Wright means that substance in the blood which, coming into 

 contact with the bacteria, so changes them that they are taken up by the poly- 

 nuclear leucocytes and destroyed. The normal serum possesses a certain amount 

 of this opsonic power, varying with the individual and the particular bacteria. 



When an infection occurs, this power will fall under the influence of the bacteria 

 which have entered. When the infection is not too strong, there will be a reaction 

 and an increased production of opsonin (a substance belonging to the group of the 

 ' bactericidal' antibodies). When the infection has passed away, or has been over- 

 come, the opsonic power of the blood is higher than it was at first, and above the 



1 Antituberculin is found in the circulating blood after the injection of tuberculin 

 though it does not occur there in cases of localized tuberculosis (Wassermann and Brack). 



