140 COLLECTED STUDIES IN IMMUNITY. 



to absorb the amboceptors, e.g., 1, i, T V, er agar culture, it will be 

 found, for instance, that the whole agar culture completely abstracts 

 the amboceptor from the serum; one-quarter of the culture abstracts 

 only part of the same, smaller amounts still less corresponding to 

 the amount of bacteria added. 



But by this method I was able to bring further proof of the specific 

 action of the immune serum. Thus when I added dead Metchnikoff 

 vibrios to the Metchnikoff immune serum, 1 was able to remove 

 the amboceptor; the serum then did not show even a trace of deflect- 

 ing action. If, however, to this Metchnikoff immune serum I 

 added other bacteria (vibrio Nordhafen, typhoid, dysentery) the 

 serum lost none of its power to deflect complement, because the 

 immune body of Metchnikoff immune serum is anchored only by 

 Metchnikoff vibrios, and not by any other kind of bacteria. 



Such an experiment is reproduced in extenso below. For certain 

 reasons to be explained directly, this requires a tedious and complex 

 method of procedure. As in the previous experiment I employed a 

 mixture of active guinea-pig serum and inactive Metchnikoff immune 

 serum (from a goat), which sufficed to kill the amount of bacterial 

 culture employed (Control II). To this mixture are added decreasing 

 amounts of the native inactive Metchnikoff immune serum of a 

 goat (column 1). The same immune serum previously treated with 

 Metchnikoff vibrios is shown in column 2; treated with Nordhafen 

 vibrios, column 3; with typhoid bacilli, column 4; and with dysentery 

 bacilli, column 5. This preliminary treatment with bacteria is as 

 follows: Agar cultures of the various bacteria are suspended each 

 in 2 cc. 0.85% salt solution and killed by heating these suspensions 

 to 65-70 for one hour. If to these four suspensions we were now 

 to add Metchnikoff immune serum with the object of having the 

 immune body absorbed, we should later, on centrifuging to remove 

 the bacteria, encounter great difficulties, it being impossible in this 

 way to obtain a clear fluid free from bacteria. The Metchnikoff 

 vibrios alone are an exception, because they are agglutinated by the 

 corresponding immune serum. Although, according to Gruber, 

 even a considerable accumulation of bacteria is without effect on 

 haemolysis, in my bactericidal experiments I met with the annoying 

 fact that such large amounts of bacteria (the centrifuged fluid is 

 cloudy) are in themselves strongly antibactericidal. I was able 

 to overcome this difficulty as follows: 2.0 cc. of the corresponding 

 inactive immune serum were added to the suspended agar cultures 



