Presence of iodinated amino acids in unhydrolyzed thyroid and plasma.

Abstract

larger amount of albumen at the disposal of the embryo is of special value in giving it a better start in life outside the capsule. Three years of laboratory culture of Ancylus fluviati, lis Muller have shown that this species has a higher percentage of abnormalities (20%) in the than any other species examined. The frequency of the different kinds of abnormal and egg cells is shown in Table 1. Most common in all three years are dwarf eggs, smaller than ordinary size (1.42x1.20 mm). Dwarf may be a phenomenon definitely connected with the starting or stopping of oviposition. In both series of eggs, those throughout the egg-laying period and those in a single capsule, dwarf are found mainly at the end of each series, but partly at the beginning. The percentages in which they occur in different positions within the capsules are given in Table 2. The considerable number of dwarf and other irregularities given in Table 1 also make Ancylus fluviatilis Muller an interesting subject for studies of the earliest phases of embryonic development. Even when still in ovo the embryos may meet with various influences that interfere with their normal development-e.g., variations in the quantity of albumen, crowding because of abnormal development of a neighboring embryo or accidental formation of nurse eggs (competition), or abnormal development of the egg cell itself, determined by intrinsic factors (e.g., lack of fertilization) or extrinsic factors (e.g., crushing of the egg cell during the formation of the capsule). The advantages of the egg capsules of Ancylus fluviatilis Muller as experimental material can be summarized as follows. The limpet is a suitable animal for studying oviposition and embryogenesis under laboratory conditions. The apparatus described makes it possible to obtain living eggs, laid in transparent capsules, for microscopic investigation of living preparations. The capsule is easily turned, and the can be studied in series exactly in the order in which they were laid. The frequency of abnormalities of several sorts in the make the capsules particularly well suited for studies of cell physiology and other aspects of experimental biology.