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In Lake Itkul situated north-westwards of the town of Abakan there were found encysted metacercariae of Apatemon annuligerum in the eyes of the perch. Adult fishes are 100% infected, the infection intensity amounting to 28 to 455 cysts (125 on the average). Maximum infection of the perch takes place at the age of 4 to 5 years. In elder fishes proceeds a decrease of infection intensity on account of a considerable mortality of cysts. There was undertaken an infection of incubative ducklings and observed a development of marita to a mature state. The maturation of eggs takes place on the 5-th day.
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The relationships between embryogenesis and the scale of living beings have been the subject of long-dated observations. It is well known that Haeckel, going back and codifying this data, has divided it into two large groups called palingenesis and coenogenesis. He has only mentioned the concept of heterochrony to which we give much more importance nowadays. We will look over these questions and link them up with some aspects of modern genetics.
The development of the cestode Khawia japonensis (Yamaguti, 1934) has been studied experimentally. At 18 to 26 C, in 12-14 days oncospheres develop in eggs, whose infective properties manifest themselves in 30-31 days. In the caudal segments of Limnodrilus udekemianus they penetrate the body cavity through the intestinal wall and migrate to the anterior margin as they mature. In 55 to 60 days (at the same temperature) mature proceroids become localized in 9-12 segments. The development of embryonal hooks and penetration glands was retraced.
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The appearance of urate oxidase activity in the Malpighian tubules of Drosophlia melanogaster is synchronized with the time of emergence of the imago from the puparium. A developmental clock within the Malpighian tubules specifies the time of appearances of urate oxidase activity.
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1. The exuvial side of the pharate pupal integument is usually positive to the haemolymph-side, both in vivo and in vitro, during the period when the moulting fluid is being secreted. 2. The ratio of potassium flux toward the exuvial space is higher than that toward the haemolymph, under both open-circuit conditions and short-circuit conditions, demonstrating by the Flux Ratio test that potassium is actively transported across the isolated integument during this secretion period. 3. Just prior to ecdysis, while moulting fluid is being reabsorbed, the potassium flux ratios become unity, suggesting that active potassium transport has ceased, but the short-circuit current that remains suggests that some other ion is actively transported at this time. 4. We argue that the potassium salt solution, formed in the exuvial space (as water presumably follows the actively transported potassium), has three functions (1) to accomplish the gel--sol transformation, (2) to activate the gel enzymes and (3) to buffer the enzyme solution at a pH favourable to the activity of the gel enzymes.
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Metamorphic vertebrate species are of particular interest in ecological and evolutionary studies because the decoupling of larval and adult growth patterns potentially allows adaptive diversifications of the separate stages. Larval and adult growth might be much more constrained if allometric patterns were constant throughout ontogeny. To better understand how differential growth patterns might contribute to tadpole diversification, we have analyzed growth allometries in relation to interspecific morphometric differences in Gastrophryne carolinensis, Acris gryllus, and Hyla gratiosa. Growth patterns in all species are significantly allometric and moderately concordant, despite many differences in detail. The species can be completely discriminated in even the smallest post-hatching tadpoles. However, the differences that distinguish the species do not seem to be a function of differential growth patterns at the tadpole stage. Rather, morphological differences ostensibly originate during embryonic development and are well established by the time the tadpoles become free-swimming.
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The relative strength of binding of several triiodothyronine (T3) analogs by cytosol prepared from the tail fin of the bullfrog tadpole has been tested and compared with their thyromimetic activity in tail tissue. In competitive binding experiments, four tri-substituted analogs were bound much more strongly than two tetra-derivatives. Correlation between binding and relative thyromimetic activity was observed only for three triiodo-substituted compounds, triiodothyronine, its methylene bridge analog and the acetic acid analog. The affinity for T3 was 250 times that of T4, making it unlikely that the T3 binding sites in tadpole tail fin cytosol bind T4 under physiological conditions. The difference in binding by tadpole tail fin cytosol constitutes one of the largest differences observed between T3 and T4 in a potentially significant biological system.
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