37 



Irst Series: 0,5 oí 16th day Precip. Serum + 0,5 of 1/2 etc. 1/128 4th day serum 1/128 



4- * 

 + « 

 + * 



+ « 



10th 

 4th 

 16th 

 10th 

 16th 



1/64 

 1/64 

 1/16 cf 

 1/16 d" 

 1/32 d- 



3rd Series of experiments: 



Four rabbits were inoculated with 

 15 cc. of normal horse-serum and were 

 bled respectively on the 6th, 10th, 16th 

 and 21th days. 



21th day serima precipitating up to 

 1/10.000 and precipitated diluted up to 

 1/32. 



16th day serum precipitating up to 

 1/10.000 and precipitated diluted up to 

 1/32 with 1/100 Antigen. 



10th day serum precipitating up to 

 1/10.000 and precipitated diluted up to 

 1/16. 



6th day serum piecipitating up to 

 1/1.000 and precipitated diluted up to 

 1/4. 



The precipitate obtained with the 

 10th day serum in the tube with 1/100 of 

 precipitinogen was slightly smaller 

 than with the 16th day serum and per- 

 ceptibly more abundant than the one 

 obtained with serum of 21 days. 



Irst Series: 0,5 of 21rst day Precip. Serum -f 0,5 of 16th day Serum (diluted up to 

 1/256) 1/64. 



2nd Series: 0,5 of 21rst day Precip. Serum + 0,5 of 10th day Serum 1/128 



3rd Series: 



4th Series: 



5th Series: 



6th Series: 



7th Series: 



8th Series: 



9th Series: 



10th Series: 



11th Series: 



12th Series: 



16th 



10th 



6th 



From these results one may infer: 



a) That precipitinogen circulating 

 in the seriun of previously treated ani- 

 mals is only demonstrable by precipita- 

 ting sera of a posterior date of bleeding. 



b) That, when in a mixtm*e of two 

 precipitating sera, the one containing the 

 more recent precipitins is taken for pre- 

 cipitant serum, precipitation never goes 

 beyond the tube in which the scrum of 

 posterior date, diluted, is able to preci- 

 pitate horse-serum at 1/100. (In the tables 

 above, the arrows indicate the sense in 

 which the precipitation produces itself; 

 the precipitation diffuses in the serima 



that acts as precipitant, provided certain 

 technical precautions are respected, 

 every time the precipitate is not very; 

 dense, which is nearly always the case.) 

 c) That, (within certain limits) the 

 precipitinogen-precipitation increases in 

 proportion to the length of the interval 

 of bleeding between the two sera. 



4th Series of experiments: 



A rabbit, inoculated with 15 cc. of 

 normal horse serum and bled at the end 

 of 26 days, furnished serum, precipitant 

 up to 1/1.000.000. 



