Studies on the Agglutinin Specificities and Blood Group O(H)‐Like Activities in Extracts from the Molluscs Pomacea paludosa and Pomacea urceus

. 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)‐like 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 .