246 MILK 



salt solution to bring the mixtures to a uniform volume and 

 incubate the series at 37 C. The titer is twice the smallest 

 amount of complement which produces complete hemolysis. 



3. Lactoserum. This is a serum from a rabbit repeatedly 

 injected with the milk. Place in each of two series of eight tubes 

 falling amounts of lactoserum, suitably diluted with physiologic 

 salt solution, in quantities of from 1 to c.c. To each tube of the 

 first series add 0.1 c.c. of milk in a dilution of 1 : 100. No milk is 

 added to the second series. Then add to each tube of both series 

 the amount of complement determined under No. 2. Place both 

 series for one hour in an incubator at 37 C. Then add to all 

 tubes 1 c.c. of the 5 per cent, suspension of washed sheep cor- 

 puscles and the amount of amfyoceptor serum determined under 

 No. 2. After mixing, incubate at 37 C. for two hours. 



The second series without milk (antigen) should show hemol- 

 ysis in all tubes. The first series should show hemolysis accord- 

 ing to the relative potency of the lactoserum. For the real test 

 that amount of lactoserum is chosen which is slightly in excess of 

 the smallest amount producing complete hemolysis. 



The Test. Place into each of a series of six tubes 



1. Falling amounts of the milk to be tested, suitably diluted 

 (0.1 to 0.00001 c.c.). No milk is placed in the last tube. 



2. The amount of lactoserum determined under No. 3. 



3. The amount of complement determined under No. 2. 

 After one hour's incubation at 37 C. add to each tube 1 c.c. 



of the 5 per cent, suspension of washed sheep corpuscles and the 

 amount of amboceptor serum determined under No. 1. As con- 

 trol, fill another series of tubes with the same mixture, omitting 

 the lactoserum. Incubate all tubes for two hours at 37 C. At 

 the end of this period all tubes of the second series should show 

 complete hemolysis. The tubes of the first series will show more 

 or less inhibition of hemolysis if a foreign milk is present. 



Anaphylactic Method. If a guinea-pig is injected with a dose 

 of a certain milk and the injection repeated after about twelve 

 days, it will show serious symptoms of poisoning and may die. 

 If a different protein is injected the second time, no symptoms 

 appear. If there is reason to suspect that goat's milk has been 

 mixed with cow's milk a guinea-pig is injected with pure cow's 

 milk and after twelve days with the suspected goat's milk. If 

 cow's milk was actually present in the goat's milk, anaphylactic 

 symptoms will appear. If the goat's milk was pure, no symptoms 

 will appear. 



Tests for Mastitis and Colostrum Milk. Milk from cows suf- 

 fering from mastitis and colostrum milk contain complement in 

 appreciable quantity, while normal milk contains only traces or 



