CONTAGIOUS El'ITHKLlOMA 205 



( "inplement. 



XoniiMl guinea piii' senuu was used as coiui)lcmeMt. It was freslilv collected 

 iMuc a week by bleeding directly from tlu^ iieart of the g-uiiiea j)igs. The 

 iMuliluted coniplenient was jireservcd with a 12 per cent solution of sodium 

 .irclatc in the proportion of 1 part sodium acetate solution to 2 parts undi- 

 hitrd eoiuplement. A 1 to I dilution of the ])reserved C()iui)lenient was used 

 U<r the preliminary eomjilement titration. One and a half times the coniple- 

 iiMiit titre was used as the working dose. 



//( iiioli/tic amboceptor. 



Shee]> liemolytic amboceptor was used. In the routine titration of the 

 aml)!)ceptor it was determined that the titre was .05 cc. of a 1-600 dilution. 

 Five units or .25 cc. were used as the working dose. 



Sheep cells. 



Freshly drawn sheep blood was agitated in a 2 per cent solution of sodium 

 citrate to prevent clotting. For this purpose from 5 to 10 cc. of the citrate 

 were used to about 80 cc. of sheep blood. The red blood corpuscles were 

 washed three times and a 2 per cent suspension of cells used in the test, 0.5 cc. 

 being added to each tube. 



Suspected or "immune'' serum. 



Difficulties were encountered in obtaining senuii separation from the avian 

 Iilood. In the first place the amount of serum obtained from the blood was 

 small, considerably less than the usual 40 per cent. This is characteristic of 

 cockerels' blood. It oftentimes "jellied" and in many cases was anticomple- 

 ir.entary. It appeared that by exercising aseptic precautions in handling the 

 serum, a great deal of this anticomplementary action was eliminated. The 

 .■-erum in many instances would also "precipitate", or present a flocculent 

 appearance during or immediately after inactivation, esjiecially if the tem- 

 perature of the inactivating bath rose above 56.5° C. The suspected .serum 

 w^as tested in doses of 0.1. cc, 0.3 cc, 0.2 cc, 0.1 cc, and 0.05 cc. 



Res-ults. 



With normal fowl serum, aside from the usual number of "Jellied" and 

 anticomplementary samples, hemolysis was complete. Tabulated residts of 

 the complement-fixation studies on the "immune" sera are too lengthy to be 

 rejiorted herein. It is sufficient to say that about one hundred and fifty such 

 examinations have been made and in no instance was it possible to obtain 

 complete fixation. Fifty per cent of the sera presented on the average a two- 

 plus fixation of complement with 0.4 cc. of serum. An occasional three-plus 

 fixation was noted in the same amount of serum. The remainder demon- 

 strated a one-plus fixation, a mere inhibition of hemolysis, or Mere entirely 

 negative (complete hemolysis). 



Precipitin Test. 



The antigens used in this test contained varying amounts of powflered pox 

 virus, ranging from 0.5 gram to 1.5 grams, suspended in 50 cc. of 0.5 per cent 

 phenolized physiological saline solution, and passed through a Seitz filter. 

 Sera from a group of fifteen birds were subjected to the test. These birds 

 had recovered from a severe experimental contagious epithelioma infection 

 and had demonstrated a complete immunity after reinoculation with the virus. 



