In 1969 an almost sterile hybrid (2n=14) between a short-day variety of 'Tossa' jute (=Corchorus olitorius; 2n=14) and a photo-neutral wild species, C, depressus (2n=14) was obtained. In F₃, approximately 80% of the plants were short-day and 20% photo-neutral suggesting that the latter character is probably recessive. A few F₃'s chosen at random for chromosome counts turned out to be tetraploids (2n=28) indicating that the F₂ parents of the F₃ population underwent chro-mosome doubling. While characters of the economic importance such as height and nonbranching habit were almost restored in the F₄ and the F₅, fibre qualities deteriorated in thern. Fibre qualities however improved in sorne backcross progeny. Further the recessive (?) character for photo-neutrality continued to segregate in F₄ and in F₅' The presence of a paracentric inversion throwing out the gene in the form of a fragment during chromatid bridge formation is suggested to be the cause for the non-fixation of the photo-neutral character in the progeny.