Saline extracts from the eggs of the snail Pomacea paludosa contain two separate and potent agglutinins specific for determinants on human ABO erythrocytes. Haemagglutinins with anti-pneumococcus type XIV and cross-reacting A and B specificities were detected in three different extracts from eggs of this species. Human group O erythrocyte-agglutinating activity of Pomacea urceus albumin gland extract was inhibited by purified hog H substance and pneumococcus type XIV polysaccharide, but purified Sassafras albidum polysaccharide was the most potent inhibitor of this reagent. Inhibition experiments with simple sugars showed that, of the compounds tested, only D-galactose, D-galactose derivatives and oligosaccharides containing D-galactose inhibited the P. paludosa and P. urceus haemagglutinins. Using anti-H reagents from different sources, blood group O(H)-Iike activity was detected in both Pomacea extracts. P. paludosa egg extracts precipitated with catfish anti-H and eel sera and P. urceus galactogen inhibited the anti-H lectins from the seeds of Laburnum alpinum, Cytisus sessilifolius, and Cytisus scoparius.

Using seven different anti-H reagents of fish and plant origin, cross-reactive human blood group 0(H)-like activity was detected in 15 of 22 invertebrate extracts examined. All of the ‘H-active’ extracts reacted with eel serum. This was demonstrated by precipitation or by the inhibition of eel serum induced agglutination of group O erythrocytes. Catfish and eel anti-H sera precipitated with the galactogens present in albumin gland extracts from five species of snails. L-fucose has not been detected in these galactogens. Precipitation reactions were also observed when some other invertebrate extracts were diffused in gel against eel serum. Based on the reaction patterns observed with the different anti-H reagents, the extracts which showed H-like activity have been divided into four different categories.