1910.] Precipitate Obtainable iyi Precipitin Interactions. 405 



Table VI. 



No. of anti- 

 serum. 



Nature of protein Used 

 for immunisation. 



Weight of precipitate 

 from 1 c.c. antiserum. 



42 

 43 

 44 

 46 

 47 

 48 

 49 

 50 

 51 

 52 

 53 

 54 

 55 

 56 

 57 

 58 

 59 

 60 

 63 

 63 

 64 

 65 

 66 



Horse serum 



Ostrich egg-white 

 Fowl's egg-white . 



)) )) 

 J) jj 

 >j )> ' 



J) J) 

 Horse serum 



)) 



» 



Fowl's egg-white . 



milligrammes. 

 1 -4 

 3-8 



2-7 



2- 4 



3- 2 



3- 9 

 1 -5 

 2-0 

 1-6 



4- 3 

 0-8 



45 



3 



3 



2 



•2 



7 



5 



•2 



16 



Further increase in the quantity of the homologous protein (in these experi- 

 ments up to 560 milligrammes protein) leads to no further increase in the 

 weight of the precipitates (Tables I and II). With other amounts of anti- 

 serum, such as 1 c.c. or 5 c.c, interacting with increasing quantities of homo- 

 logous protein, similar phenomena are observed. The weights of the precipi- 

 tates rise to a maximum and then remain constant. 



When the amounts of antiserum are varied, the weights of the precipitates 

 are directly proportional to the amounts of antiserum as soon as the quantities 

 of homologous protein are sufficient to produce the maximal precipitates 

 (Table III). These quantities of homologous protein are those which 

 neutralise completely the precipitin in the antiserum. The superfluids from 

 such interactions fail to yield precipitates on the addition of any quantity of 

 homologous protein. If the quantity of homologous protein be insufficient to 

 neutralise all the precipitin in the antiserum, the weight of the precipitate is 

 diminished and the addition of a further quantity of homologous protein to 

 the superfluid leads to the formation of a precipitate. When tlie precipitin 

 is neutralised in two or more stages by further increments of homologous 

 protein, the weight of the combined precipitates is equal to that of the pre- 

 cipitate formed in a single interaction with a quantity of homologous protein 

 sufficient to neutralise completely the precipitin (Tables II and III). 

 VOL. LXXXII. — B. 2 K 



