1911.] On the Factors Concerned in Agglutination. 419 



As regards conglutination and agglutination it appears that the action of 

 ox colloid and complement is to intensify the effect of an agglutinin present in 

 a normal or an immune serum, such action being of the nature of com- 

 plementing. It is necessary for conglutination that the cells should be 

 sensitised. Muir and Browning, in fact, expressed the view that the ox 

 serum acted as a complement to the immune serum. 



The interaction of the various factors in agglutination and conglutination 

 finds to some extent a parallel in phagocytosis, in which the action of a 

 heated serum is intensified by the addition of complement. 



General Object of the Experiments. 

 The experiments here recorded were undertaken as the result of a chance 

 observation. A number of experiments had been made with the view of 

 ascertaining the relative quantities of the two fractions of complement 

 necessary for the production of hsemolysis. In such an experiment it is, of 

 course, essential to put up control tubes which contain the various dilutions 

 of the middle-piece and of the end-piece in order to make certain that 

 neither fraction acting by itself can produce hsemolysis. It was noticed 

 that the corpuscles in the middle-piece control tubes presented a remarkable 

 appearance. Instead of settling down to form a small mass at the very 

 bottom of the tube, the corpuscles were found to be arranged in a thin layer 

 which coated the bottom end and lower part of the tube. The layer of 

 corpuscles took the shape of the lower part of the tube and produced the 

 •appearance of a small cup. If the tube was sharply shaken it could be seen 

 that the corpuscles had been agglutinated. The control tube which con- 

 tained corpuscles and immune body without the middle-piece solution 

 showed no agglutination. The agglutination had been produced by the joint 

 action of the inactivated hsemolytic serum and middle-piece solution. 



Method of Preparation of Experimental Material. 

 Preparation of Complement Fractions — 



In the experiments which are to be described the complement fractions 

 have been obtained by the carbon dioxide method of Liefmann (1909). 

 Fresh guinea-pig serum is diluted with distilled water in the proportion of. 

 one part of serum to nine parts of distilled water. The mixture should be 

 kept cold in an ice bath, and it is an advantage to prepare the mixture with 

 ice-cold distilled water. The mixture is saturated with carbon dioxide and 

 then allowed to stand for one hour in the cold room. The carbon dioxide 

 produces a marked turbidity in the mixture, and at the end of the hour's 



