The behaviour of mouse spermatozoa in solutions of low electrolyte content was different from that reported for the rabbit. Mouse spermatozoa, suspended in isotonic solutions of glucose, sucrose and fructose, showed no tendency to agglutinate tail-to-tail (as occurs with rabbit spermatozoa) but became permanently immotile within 10 to 15 min.
A species of bacterium (Pseudomonas maltophilia) was discovered which caused an intense agglutination of mouse spermatozoa resembling an antibody agglutination. A serially diluted culture of bacteria produced an agglutination reaction whose end-point was dependent on the concentration of spermatozoa used for the test. Spermatozoa became agglutinated head-to-head, tail-to-tail, and head-to-tail. The agglutination involved the bacteria themselves and not a product of their growth.
Five additional strains of P. maltophilia were examined. Four of these strains also caused agglutination of mouse spermatozoa, one strain did not. Three members of the genus Serratia were capable of agglutinating mouse spermatozoa and one other was not.
In addition to mouse spermatozoa, P. maltophilia agglutinated spermatozoa of the rabbit strongly and of the human slightly.