Three hybrids, two ofHordeum jubatumL. ×Secale cerealeL. var. Prolific, and one ofH. jubatum × H. bulbosumL., were examined cytologically. The two genomes ofH. jubatumshowed autosyndesis in theH. jubatum × S. cerealehybrids. It was concluded, therefore, thatH. jubatumhas two closely related genomes.One of theH. jubatum × S.cerealehybrids displayed weak asynapsis. TheH. jubatum × H. bulbosumhybrid, on the other hand, showed strong asynapsis, although the prophase pairing was almost complete. It was concluded that the asynapsis of this latter hybrid was due to interaction of genes of theH. jubatumand theH. bulbosumgenomes.The chiasma distributions of the hybrids were tested for randomness by Gaul's formula. It was found that the chiasma distributions of theH. jubatum × S. cerealehybrids followed a random pattern, whereas in theH. jubatum × H. bulbosumhybrid the distribution was disturbed by a secondary effect. Cytological observations and theoretical considerations led to the conclusion that the occurrence of pseudo ring-bivalents had disturbed the apparent chiasma distribution in theH. jubatum × H. bulbosumhybrid. A theory of the origin of pseudo bivalents and an evaluation of Gaul's formula is presented.