ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04259.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04260.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04261.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARY1In 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.2These 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).3It 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 Well

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04262.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04263.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04264.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARY1The stem eelworm,Tylenchus dipsaci(Kuhn) Bastian, is a severe pest on a variety of crops.2Usual symptoms of attack constitute dwarfing, distortion and frequently chlorosis of the host plant.3The biology of the eelworm is essentially the same in nearly all host plants.4Infection may take place immediately after leaving the previous host, or after a period of enforced quiescence.5Examination of available data indicates that, while biologic strains or races of the eelworm do exist, these strains show varying powers of adaptation to other host plants.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04265.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04266.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARY1The rate of carbon dioxide production byB. prodigiosusfrom various sugars has been studied and an account of experiments conducted with a view to finding out the factor or factors responsible in lowering the carbon dioxide production in soil and solution is given.2It is found thatB. prodigiosuscan decompose glucose and laevulose most readily while sucrose comes next in order. Lactose and maltose are very slightly decomposed.3The amount of carbon dioxide produced is not equivalent to the amount of sugar used up. Other organic products like alcohol, acetone and organic acids are produced.4Carbon dioxide production always attains its highest limit within the first three or four days and then declines rapidly in spite of the presence of sugar and active organisms.5Successive additions of fresh quantities of sugar to solution cultures when the carbon dioxide production has reached its minimum rapidly increase the carbon dioxide formation to a value practically identical with that previously attained.6It appears that exhaustion of total or readily available carbon, formation of an unattackable film on the surface of particles of organic matter, or exhaustion of available mineral constituents is not responsible for lowering the carbon dioxide production in soil.7Additions of organic matter such as glucose' or oil cake to soil after the carbon dioxide production has declined, restores the process practically to the same level as at the start.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04267.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARYFrom pot culture experiments in the greenhouse it has been shown that the formation of nodules on the roots ofCrotalaria junceais affected significantly by variations in the texture, moisture content and reaction of the soil, all other conditions being kept uniform. Nodule formation was increased by higher moisture content, by increased coarseness and by reduced hydrogen ion concentration.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04268.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY