Abstract
Meiosis in males heterozygous for inversions was studied in 22 species of Chironomids. An inversion loop is not regularly formed at pachytene, instead, the inverted region pairs non-homologously in some cells. The frequency of non-homologous pairing appeared to be high in those cases where an estimate could be made. This appears to be an important factor in the prevention of inviable gametes due to crossing over within the inverted region. Although more important in males, it apparently occurs also in females.