A Note on the Agglutination of Meningococcus *

Agglutination by monovalent serum is the method customarily employed to establish the type diagnosis of meningococcus. The test is simple and, in certain of its modifications, quite rapid. It is even applied by some bacteriologists directly to any gram-negative diplococci encountered in primary culture of the upper respiratory tract before their species has been determined by sugar fermentation tests. Re-examination of all phases of the method seemed, therefore, to be warranted. This was done in a series of experiments recently carried out, the results of which are described below, together with some data bearing on the subject of agglutinin-production gathered from a long series of experiments that -have been in progress for a number of years. As the experimental data are too extensive to be detailed in a communication of this length, they will be presented in summary form although they have not been published heretofore.