XXX. THE TECHNIQUE OF BACTERICIDAL TEST- 

 TUBE EXPERIMENTS. 



By Professor M. NEISSER, Member of the Institute. 



IN order to measure the bactericidal power of a serum or of 

 serum mixture by means of a test-tube experiment, the plate method 

 (Neisser, Buchner) is still the safest. Only in special cases can one 

 obtain useful comparative results by other methods (observing 

 hanging drops for the onset of granular degeneration, R. Pfeiffer, 

 or bioscopic method, M. Neisser and Wechsberg *). But even the plate 

 method at present is cumbersome and, what is of more consequence, 

 is not applicable in all cases. It is not a sensitive method and is only 

 then useful when marked results are to be expected in consequence 

 of strong bactericidal powers. As a rule such marked results are 

 only to be attained with immune sera and only rarely with normal 

 sera. 



So far as immunization is concerned it is impossible to make 

 general statements, and I shall therefore only cite a few examples. 

 Thus in the case of chlorea vibrios a single subcutaneous injection 

 of three dead agar cultures into rabbits gives good results (R. Pfeiffer 

 and Marx 2 ), as does also the intravenous injection of extremely small 

 quantities (Mertens, R. Pfeiffer 3 ). In immunizing against typhoid, 

 dogs and goats are most useful. In this case a single injection of 

 dead cultures does not suffice in order to obtain a high-grade bac- 

 tericidal serum; on the contrary repeated injections of living cul- 

 tures are necessary. For obtaining a serum having strong bac- 

 tericidal properties against Shiga's dysentery bacilli, horses are well 

 adapted; goats very much less so; rabbits and guinea-pigs are very 



1 Miinch. med. Wochensch. 1900, No. 37. 

 1 Zeitschr. f. Hygiene, XXVII, 1898. 

 3 Deutsche med. Wochensch. 1901. 



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