( 36 ) 



toxin) are added. There upon the mixtures are heated for one 

 hour at 37° and then centrifugated in funnelshaped tubes of which 

 the capillary neck was fused at the bottom. The in 100 equal volumes 

 calibrated capillary portion contains 0.02 or 0.04 c.c. The centri- 

 fugating is continued till the volume of the precipitate has become 

 constant ^). 



Experiment with calf -horse serum. 



As it was of importance, at all events for the first series of proofs, 

 to dispose of a great quantity of serum containing precipitin, a large 

 animal was taken to be injected. Dr. M. H. J. P. Thomassen at Utrecht 

 was so kind to inject at the Governement Veterinaryschool there, 

 a large calf several times with fresh horse serum and to prepare 

 the serum out of the blood drawn under asceptic precautions. 



The serum used for the following series of experiments was 

 collected Nov. 28, 1905, sent to Groningen and there presei'ved in 

 ice. On the day of the following experiment January 25, 1906, 

 the liquid was still completely clear and free from lower organisms ; 

 there was only on the bottom a thin layer of sediment, which 

 naturally was carefully left behind at the removing of the liquid. =■) 



The horseserum used for the proof in question was fresh and 

 50 times diluted with a sterile NaCl-solution of 17o- 



Each time two parallel proofs were taken as a control. The 

 capillary portion of the funnel shaped tubes used for this experiment 

 had a calibrated content of 0.04 cc. Each division of the tubes thus 

 corresponded to 0.0004 cc. 



To this series of experiments another was connected in which the 

 quantity of diluted horseserum was constant, but increasing quan- 

 tities of calfserum were used. 



From the tirst table it appears, that when to 1 cc. calfserum 

 increasing quantities of diluted horseserum are added, the quantity 

 of precipitate rises. When more horseserum is added as is the case 

 in the second table, the quantity of precipitate descends. This appears 

 from the following. 



1) Compare Folia haematologica 1. c. for further particulars of the method. 



2) Fuller details of other proofs taken on other days with calf-horseserum, also 

 of experiments with serum obtained by injecting rabbits with pig-, oxen-, sheep- 

 and goat-serum will be communicated elsewhere. 



