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INFLUENCE OF LEAD AND THE METALLIC IONS OF COPPER, ZINC, THORIUM, BERYLLIUM AND THALLIUM ON THE GERMINATION OF FROGS‘ SPAWN AND ON THE GROWTH OF TADPOLES 1
Author(s) -
DILLING WALTER J.,
HEALEY C. W.
Publication year - 1926
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1926.tb04262.x
Subject(s) - germination , copper , biology , zinc , lead acetate , metal , thallium , toxicity , beryllium , nuclear chemistry , radiochemistry , metallurgy , botany , chemistry , materials science , organic chemistry
SUMMARY1 In these experiments lead salts proved to have a higher inhibitory influence on the germination of the frog's ovum than the salts of other metals tested and they also proved capable in weaker solutions of retarding the growth of tadpoles without causing their early death. Of the other metals tested thorium was active in checking germination; the others much less so. Zinc, copper and thallium were more toxic to the emerged tadpoles than lead. Beryllium was relatively inert. Hanzlick and Presho's observations on pigeons fed with pure metals led them to conclude that, as regards the power of reducing body weight, the action of other metals was much less than that of lead, which they regard as having a specific toxicity (6). The present writers do not consider that these effects are “specific” or peculiar to lead, but they are relatively more marked with its salts. Locke's (9) experiments with tadpoles showed that lead was less directly toxic to them than zinc and much less than copper; this we have confirmed, but our experiments suggest that the “oligodynamic” action of lead decreases as the embryo ages. 2 These experiments suggest that lead is more toxic to germinating tissues than the other metals tested and afford an explanation of its abortifacient action on the basis that it is much more toxic to the embryo than to the adult tissues of the parent. Subsequent experiments by Blair Bell, Hendry and Annett on pregnant rabbits have shown that after injections of colloidal lead there occurs a coagulation necrosis in the ectodermal tubules (trophoblast) of the foetal placenta; this rapidly spreads throughout the foetal ectoderm and into the adjacent superficial tissues of the maternal placenta so that the necrotic foetal placenta is soon cast off. They conclude that lead has a selective affinity for the chorion epithelium and that abortion can be produced by the action of lead on the foetal ectoderm (trophoblast) without the maternal organism being in any way affected.On the findings of the present experiments these observers tried thorium as a substitute for lead but found it had no specific or toxic action on the chorion epithelium and that the abortifacient action of copper and thallium was uncertain and due to haemorrhage in the maternal tissues of the uterus (2).3 It has also been possible to confirm by these experiments some of the essential features recorded in the literature, e.g . ( a ) the toxicity of lead towards the female germ cell as higher than that to the male cell as was indicated in Weller's (15) experiments; ( b ) the greater susceptibility of very young animals to lead and progressive tolerance as the animal ages; and ( c ) the retardation of growth in the tadpole is comparable with the undersized offspring delivered from the mammal and the retardation of growth noted after birth by Weller (16).