Date of this Version
As part of a study (supported in part by the U. S. Atomic Energy Commission Contract No. AT(40-1) 1749) of the effects of radiation upon cestodes, we considered the possible usefulness of chromosome aberrations as a measure of radiation damage. Because of the small size of the chromosomes and the peculiar technical difficulties of this material, we cannot rely on chromosomal iadications; nevertheless we wish to report what we know of the chromosomes of Hydatigera taeniaeformis and Taenia pisiformis. Since the early inconclusive work of Harman (1913, J. Morph. 24: 205-242) there has been no published report on these chromosomes.
All ordiuary cytological techniques were tried but only one, Schreiber's (1954, Stain Tech. 29: 285-291) feulgen-aceto-carmine method, gave good results. The chromosomes of Hydatigera taeniaeformis number 16 diploid, and range in size from about 1 to about 2 microns. In meiosis, they form eight bivalents, with one, seldom two, chiasmata each (see Figs. 1-3, 8). The chromosomes of Taenia pisiformis number 20 diploid, and are somewhat larger than those of H. taeniaeformis. They form bivalents regularly, some of which may have as many as four chiasmata (see Figs. 5-7, 9).