On the factors concerned in agglutination

Of the various reactions which can be observed to take place between antigen and antibody, agglutination has usually been looked upon as relatively simple. It has been assumed that the clumping of bacteria or red cells is produced by the action of substances known as agglutinins. According to the well-known views of Ehrlich, an agglutinin is possessed of two groups, a cytophile or haptophore group which fixes on to the cell, and a group which has the property of producing agglutination. According to another view the cell or bacterium combines with its specific antibody, and the combination of cell and antibody is then clumped by the action of electrolytes. A broad distinction has, however, always been drawn between such phenomena as precipitation and agglutination, which appear to represent a comparatively simple reaction between antigen and antibody, and those more complex effects such as hæmolysis and bacteriolysis in which another the specific action of the antibody. Observations published by Muir and Browning (1906) suggested, however that in some instances, at any rate, the mechanism of agglutination may be more complex.