The Blood-corpuscles 291 



The blood soon coagulates when undisturbed, and in a short time 

 clear serum exudes from the clot. As, however, the complement 

 seems to be at least in part derived from the corpuscles, the serum 

 should not be removed as soon as it forms, but permitted to remain 

 in contact with the clot for three hours. If it is desired to save 

 time, the clot, as soon as formed, may be cut into strips and placed 

 in the tubes of a centrifuge and whirled for a half-hour. This se- 

 cures a greater quantity of the serum and at the same time gives it 

 its full value, probably by injuring the leukocytes. 



Such serum containing the complement is useful for twenty-four 

 hours. Should it be necessary to be economical with the guinea- 

 pigs, any serum not used may be preserved with a fair amount of 

 success by freezing. This was first suggested by Morgenroth, and 

 improved by Weston* as follows : The guinea-pig serum, having been 

 three hours in contact with the clot, was placed in thick-walled test- 

 tubes 10 X 100 mm., two cubic centimeters in each tube. The 

 tubes were closed with tightly fitting cork stoppers. A cake of arti- 

 ficial ice, left in the can and surrounded by brine was set aside for 

 the preservation of the serum. A hole was made in the ice, the 

 tubes placed in it so that the cork stoppers just reached the top 

 and ground ice was packed around them. One out of three tubes 

 kept its complementary value unchanged for three months. 



Rhamyt found that chemically pure sodium acetate had no hemo- 

 lytic properties and could be used to preserve serum without loss of 

 its complementary power. He used a 10 per cent, solution of the 

 sodium acetate in 0.9 per cent, sodium chloride solution for preparing 

 the usual 40 per cent. ■ dilution of the complement, and found that 

 the complementary value of the serum was preserved until the solu- 

 tion was used up in routine work. In one month the deterioration 

 of complementary value was so slight that the dose of serum had 

 only mcreased to 0.125 instead of its original o.i. The complement 

 should, however, be titrated witli each new batch of blood corpuscles 

 to make sure of the possible variation in value. The quantity of 

 the complement in the serum of the guinea-pig is fairly constant, 

 when the animal is regularly fed, and furnishes a fairly uniform 

 reagent that requires no titration. 



11. For the second, or hemolytic, test two additional reagents 

 are required: 



Blood-corpuscles to be dissolved. 



Hemolytic amboceptors by which complement may be 

 united to them. 



(4) The Blood-corpuscles. — It makes no difference what kind of 

 blood-corpuscles are employed. Ehrlich and Morgenroth, in their 

 pioneer experiments into the mechanism of hemolysis, used goat 

 corpuscles. Bordet used rabbit corpuscles; Wassermann, Neisser, 



* Jour. Med. Research, 1915, xxxii, p. 391. 

 t Jour. Amer. Med. Assp., 1917, ixk, p. 973. 



