1910.] Precipitate Obtainable in Precipitin Interactions. 401 



Here the antiserum was formed by the injection of fowl's egg-white and 

 the fresh antiserum allowed to interact with fresh egg-white. A portion of 

 the ess-white was dried to determine the solid content of the solution. The 

 precipitates are stated in terms of the amount yielded with 1 c.c. antiserum. 

 The weight of precipitate remains practically constant, although the protein 

 increases from 14 to 432 grammes. A somewhat similar series is recorded in 

 Table II. In this series, 3 c.c. antiserum were allowed to interact with 

 70, 140, 280, and 560 milligrammes dried egg-white. After 24 hours the 

 superfluids were removed, and to the superfluid of the tube No. 1 (1b in 

 table), 70 milligrammes dried egg-white were added; to that of the tube No. 2 

 (2b in table), 140 milligrammes dried egg-white were added, and the 

 remaining two tubes were tested in the usual way. The precipitates were 

 treated in the manner above described, and weighed. No precipitates 

 occurred in the secondary superfluids of tubes Nos. 3 and 4. 



Table II. 



No. of 

 tube. 



Weight of 



dried 

 egg-white. 



Amount 

 of anti- 

 serum. 



Amount 

 of saline 

 solution. 



Weight of 

 precipitate. 



Total weight 



of the 

 precipitates. 



Total weight 

 of precipitate 



from 1 c.c. 



antiserum. 



1. 



2 



2b 



3 



4 



milligrammes. 

 70 

 + 70 

 140 

 + 140 

 280 

 560 



c.c. 



3 



3 



3 

 3 



c.c. 

 50 



50 



50 

 50 



milligrammes. 



2 -8 

 0-7 



3 -2 

 trace 



3 -0 

 3-2 



milligrammes. 

 } 3-5 



1 3-2 



3-0 

 3-2 



milligrammes. 

 1-16 



1 -06 



1 -0 

 1 -06 



The superfluids from tubes 1b and 2b were tested for the presence of 

 precipitin by the addition of more protein, but no precipitates were obtained. 

 In this series the weight of precipitate obtained from 1 c.c. antiserum 

 remains constant, despite the large increase in the quantity of protein. No 

 stress can be laid on the amount of precipitate in tube No. iB, since it is 

 doubtful whether the interaction in tube No. 1 was complete in 24 hours. 



As it appears that the precipitate from a given quantity of antiserum is 

 constant, provided there be sufficient protein to neutralise the precipitin, a 

 series of experiments in which the amount of antiserum was varied may be 

 considered. With these experiments may be considered one in which a 

 duplicate was carried out. The details of the experiments were varied to 

 avoid errors. The results are recorded in Table III. 



The quantity of protein was found to be sufficient to neutralise all the 

 precipitin except in tubes Nos. 11, 12, and 13. The results show that the 



