摘要:

SUMMARY1Blotchy ripening of tomato fruits is the result of malnutrition in respect of potash and nitrogen, especially the former. Phosphates seem to be unimportant in this respect.2The proportion of blotchy fruits may be reduced to less than 1 per cent, by suitable applications of sulphate of potash and sulphate of ammonia.3Blotchy ripening has not been eliminated entirely by manurial treatment. Other factors, probably climatic in nature, play some part in the incidence of this disorder.4Root invading fungi, such asColletotrichum tabificum, interfere with the feeding of the plant and indirectly cause blotchiness of the fruit.5Exposure of the fruits to excessive sunlight causes a type of blotchiness known as “green back” if the nitrogen and potash supply is inadequate.6Blotchy ripening may be accompanied by necrosis of the vascular bundles of the fruit and breakdown of the adjacent tissues with the formation of canals.7A deficiency of nitrogen and potash in the soil in which tomato plants are growing causes distinctive colour changes in the leaf.8The leaves of tomato plants grown in soil deficient in nitrogenous foods, develop pale yellow blotches between the veins. The blotches gradually increase in size until the entire leaf surface is yellow.9Leaf scorch, characterised by a paling and subsequent desiccation of the leaf margin is due to potash starvation.10When potash is absent from the nutrient supply, the severity of leaf scorch increases as the nitrogen and phosphate supply is increased.11Leaf scorch can be eliminated completely by the application of sulphate of pot

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04280.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARY1Diagnostic characters which have been found of use in distinguishing samples of wild white from Dutch clover seed:(a) Frequency with which certain shape types of seed occur in each sample.(b) Average ratio of long diameter of seed to short diameter.(c) Area of cotyledon.(d) Length of petiole of first foliage leaf.2All samples, all individuals of one sample, or of one head of wild white clover, do not give a positive reaction for the cyanophoric test.3Further diagnostic characters at a later stage of growth, (a) prostrate habit, (b) formation of axillary shoots, are characteristic of wild white clover.4Permanence in wild white clover is due to a strongly developed power of vegetative propagation. Dutch clovers are not permanent as they lack this power to different extents.5Loss of permanence in cultivated white clover is due to unintentional selection of the non‐permanent type (by the grower), and to cross‐fertilisation by the non‐permanent or Dutch plants growing in the neighbou

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04281.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.tb04282.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARYIt is observed that on whatever media the organism is growing, whether in liquid or agar or in soil, the various stages of the life‐cycle are found to occur simultaneously, but in varying proportions. The soil conditions, such as aeration, temperature and the presence of certain salts, are among the factors that determine which of the stages shall be in predominance. The relative efficiency of liquid and solid media in bringing about the predominance of a particular form was also studied.In the main, the existence of the five stages in the life‐cycle of the organism observed by Bewley and Hutchinson is confirmed; but evidence is obtained to show that under very favourable conditions the motile cocci (“swarmer”) can emerge directly from the banded rod stage, developing flagella even, before their emergence, and therefore missing out the non‐motile (“pre‐swarmer”) stage.The appearance of coccoid bodies is observed to have been accelerated in the presence of saccharose, mannite and phosphates (in agar media) and also in soil extract alone. Short rods are elongated cocci and they tend to persist in media containing the ingredients mentioned above.The formation of “pre‐swarmers” has been ascribed to unfavourable conditions, such as deficiency of food, or excess of calcium carbonate in the media, or inadequate aeration. A closer study of the morphological variations, however, shows that the banded rods are associated with such conditions.Comparing the morphological variation with the number of organisms in a given time, it appears that changes in morphology are accompanied by marked alterations in the bacterial activity. The percentage increase of cocci and short rods in soil is found to be correlated with an increased total number of organisms.The writer wishes to acknowledge his indebtedness to Mr P. H. H. Gray for giving him much valuable advice and criticism in the course

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04283.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARY1Four hundred and seven young albino mice produced in 66 litters had an average weight of 1.41 gm. at birth and of 7.14 gnu at weaning time (3 weeks old).2These average values vary very considerably, but uniformly according to size of litter. Individuals from litters of 2 and litters of 10 averaged respectively 1.0 gm. and 1.6 gm. at birth, and 4.45 gm. and 11.75 gm. at weaning time. Individuals from the intermediate sizes of litter grade fairly evenly in between these extremes. The whole growth during suckling is in fact inversely proportional to the size of litter.3Growth during suckling is characterised by the active phases in the first and third weeks respectively and a comparatively stagnant period in between.4These results can all be explained on a basis of differential nutrition.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04284.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.tb04285.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARY1Insect pests in the Hawaiian Islands are, with few exceptions, immigrant species from other countries. Their control by biological methods dates from 1890, when A. Koebele introducedNovius cardinalisfor repressing the cottony cushion scale,Icerya personas, and the experiment was completely successful.2The sugar cane leafhopper,Perkinsiella saccharicida, has been suppressed by the combined activities of several imported species of Chalcid egg‐parasites, followed by the introduction of the predaceous Capsid,Cyrtorhinus mundulus, from Fiji and Queensland.3Satisfactory control of the sugar cane borer,Rhabocnemis obscurahas been achieved in most infested areas by the TachinidCeromasia sphenophori, introduced from New Guinea. In certain districts, under bad climatic conditions, outbreaks still occur and efforts are being made to meet the situation by introducing other beneficial insects.4Efficient control of the beetle,Anomala orientalishas been obtained by the introduction of the wasp,Scolia maniliaefrom the Philippines. This pest has not since increased to its former destructive proportions.5The Avocardo mealy bug,Pseudococcus nipae, affords one of the most recent examples of biological control. Since the importation of the Chalcid parasitePseudaphycus utilisfrom Mexico in 1922 this pest has been difficult to find in many districts.6The indigenous Pyralid leaf‐rollersOmiodes acceptaand O. blackburniare no longer pests of serious consequence. They are controlled by several enemies, chief among them being the Braconid,Macrodyctium omiodivorumand the Chalcid,Chalcis obscurata: both parasites were originally obtained from Japan.7Satisfactory repression of the Mediterranean fruit fly,Ceratitis capitata, has yet to be achieved. The importation of parasites from Africa and Australia has markedly decreased the infestation, but their efficiency appears to be partly neutralised by the species competing against one another and supra‐parasitism is prevalent.8The Australian fernweevil Syagrius fulvitarsisno longer occasions damage to tree ferns to its former extent. The recent introduction of the BraconidIschiogonus syagriifrom Australia has brought about this result.9Early introductions of various Coccinellidae, more particularly ofCryptolaemus montrouzieriandCoelophora inaequalis, resulted in the complete subjugation of certain coccids and aphides.10Promising results are being obtained against army worms and cutworms by the recent introduction of the ChalcidEuplectrus platyhypenaefrom Mexico. The breeding and liberation of this parasite are still being carried out.11Control of wireworms and the horn fly has not, so far, met with success.12The colonisation of a number of species of insect enemies ofLantana, from Mexico, afford the first example of pest plant control by this method. The restraint which they have exercised, more especially by prevention of seeding, has checked that plant reinfesting areas previously cleared.13The repression of nut grass (Cyperus rotundatus) by the introduction of insect enemies from the Philippines is being carried out as a preliminary experiment and a survey of the possibility of controlling Pamakani (Eupatorium glandulosum) has been made in its Mexican ha

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04286.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARY1An account is given of laboratory experiments on the toxicity toAphis rumicisL. of extracts of a considerable number of plants, including some tropical fish‐poisons, Lupins, Broom, Gorse, Lobelia and others.2Alcoholic extracts of certain tropical plants used as fish‐poisons are shown to have a high toxicity under the conditions of the experiments. The roots and stems of White Haiari, and the stems of Black Haiari (both species ofLonchocarpusfrom British Guiana), the roots ofTephrosia toxicariaand the leaves ofT. Vogeliiall possess notable insecticidal properties. The roots and stems ofT. Candidaare less toxic.3Preliminary experiments indicate that the Haiaris andT. VogeliiandT. toxicaria, when tested as stomach poisons, exert both a repellent and toxic action to caterpillars.4Certain derivatives isolated from these plants were tested. The most toxic substance obtained from the Haiaris is shown to be identical with tubatoxin, the crystalline poison found inDerris elliptica.Tubatoxin proved to be several times more toxic than nicotine. In the case ofTephrosia VogeliiandT. toxicaria, the most toxic substances isolated were resinous in nature. Crystals closely corresponding to tephrosin, as isolated by Hanriot, were less toxic.5A number of alkaloids was also investigated. Cytisine and lobeline, known to have a physiological action on higher animals similar to that of nicotine, were found somewhat less toxic than nicotine to aphides. Eserine was the only other alkaloid tested which approached nicotine in toxic

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04287.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARY1The toxicity of 3: 5‐dinitro‐o‐cresol and its sodium salt to eggs of the mothSelenia tetralunariaHüfn, has been determined quantitatively under controlled conditions in the laboratory. The figures obtained confirm earlier results and show (a) that these compounds have a very high toxicity to insect eggs, and (b) that the sodium salt of dinitro‐o‐cresol is only slightly less toxic than dinitro‐o‐cresol in the uncombined state. The relationship between concentration and toxicity is expressed by means of diagrams.2Preliminary laboratory experiments indicate that dinitro‐o‐cresol is also highly toxic to insect eggs of a more resistant type than those ofS. tetralunaria.3Spray fluids containing dinitro‐o‐cresol or the sodium salt showed a high efficiency against eggs of the Hop‐Damson Aphis (Phorodon humuliSchr.) on plum trees on a larger scale under field conditions. The trees sprayed with these compounds remained almost free from aphides during the following spring when the control trees were badly infested.4A quantitative method for judging the results of the field experiments was worked out. This involved recording details of large numbers of eggs on selected shoots on sprayed and control trees before and after spraying, a numerical measure of the effect of the various treatments being thus obtained. The method gave consistent and reliable results.5The spray fluids containing dinitro‐o‐cresol and its sodium salt had a marked general cleansing effect on the trees. No inju

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04288.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

Ordinary Meeting of the Association, Friday, November 20th, 1925, Prof. V. H. Blackman, F.R.S., President, in the Chair.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04289.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY