The methods used to create tetraploids are similar to those used to produce triploids, except that the heat or pressure shocks are applied at a later developmental stage. Malison's group has produced several hundred perch that have four chromosome sets. They are now waiting for them to mature, a long process, because the tetraploids seem slow-growing and weak. Malison says this is probably due to the shock they received rather than because of their altered genetic structure. If successful, the tetraploid/diploid pairing will result in triploid perch that never received heat or pressure shocks. The technique should eliminate the drawbacks produced by the direct shock method.