Behaviour of Precipitins in the Body 127 



time for an increase of precipitin after the fall which succeeded the 

 last injection. The maximum of the precipitin content usually appears 

 to be reached about eight days after the final injection. 



Following upon a period which may last two weeks or longer, the 

 precipitin content gradually begins to fall, in animals which have 

 ceased to receive treatment. Thus Strube (12, vi. 1902), who studied 

 eight animals in this respect, found that they furnished for about a month 

 sufficient precipitin to produce a reaction in a blood dilution of 1 : 1000, 

 but that after eight weeks the precipitin had disappeared, and that 

 then it was possible to again treat the animals with the same blood, 

 and again obtain precipitin. Rostoski (1902, b, p. 39) found scarcely 

 a trace of precipitin in the sera of animals 13 weeks after the last 

 injection. The precipitins do not therefore appear to persist as long 

 in the body as do, for instance, the agglutinins. 



In animals subjected to long-continued treatment, the precipitins 

 may be seen to gradually disappear, as was noted by Tchistovitch 

 (v. 1899). I have not found a similar observation recorded in publica- 

 tions by other writers, although I was able to confirm it a year ago 

 (Nuttall, 16, xii. 1901, p. 407) in some rabbits which I treated with 

 human serum, in the false hope of increasing the strength of the 

 antiserum they possessed. As I wrote at the time, " There is therefore 

 a point in the treatment of animals, for purposes of obtaining an 

 antiserum, when a maximum of power is reached, and the animal 

 should be bled." 



That the precipitins are present in other body-fluids besides the 

 serum is indicated by an observation of Eisenberg's (v. 1902, p. 308) 

 who twice found precipitins in the humor aqueus of rabbits treated 

 with fowl-egg injections. As far back as 1888 I noted the existence of 

 normal bacteriolytic substances in the aqueous humour, and I might 

 add that other antibodies, e.g. typhoid agglutinins, have also been found 

 in this situation by Levy and Giesler. Eisenberg, and Moro, (31, X. 1901 

 in milk-treated rabbits), were unable to find any precipitins in the urine 

 of their immune animals. It would however be a matter of interest 

 to see if they appear in the urine of rabbits suffering from albuminuria 

 following upon injection with foreign albumins, even though there may 

 be but a moderate amount of precipitin in their blood. I propose to 

 investigate this. 



The precipitins are transmitted to the offspring in utero, as was first 

 shown by Mertens (14, III. 1901) who examined the serum of one out of 

 three newborn rabbits for precipitins, the mother having been treated 



