1. The polysaccharide fractions from each of five yeast-like fungi produce rapid, fatal anaphylactic shock in guinea pigs passively sensitized with antiserum from rabbits immunized against the killed organisms.
2. Cross-anaphylactic reactions with heterologous polysaccharide fractions are frequent. They parallel closely the cross-precipitin reactions, thus adding evidence in favor of the identity of precipitin and sensitizing antibody.
3. The polysaccharide fraction from Monilia psilosis produces anaphylactic death in guinea pigs actively sensitized with killed homologous organisms, but an attempt to sensitize actively with the polysaccharide fraction was unsuccessful.