thread-reac'tion

[Ger. FadenreaktionJ] If a drop of blood from a person suffering or convalescent from typhoid fever is added to a suitable medixmi inoculated with typhoid bacilli, the latter exhibit a tendency to arrange themselves in chains or threads; the reaction is present, but incomplete, in the case of a person who has had typhoid fever a number of years before. The phenomenon is observed in the case of other bacteria also when growing in a specific serum it is supposed to be due to the presence of agglutinins in the serum.