SOME MICROBIOLOGICAL STUDIES OF TWO SPECIES OF APHIDS, APHIS FABAE SCOP. AND MACROSIPHUM PISI (HARRIS) (HEMIPTERA, HOMOPTERA: APHIDIDAE)

1963 ◽  
Vol 9 (1) ◽  
pp. 65-73 ◽  
Author(s):  
N. N. LeBlanc ◽  
A. J. Musgrave
Keyword(s):  
Aphis Fabae ◽  
General Body ◽  
Histological Sections ◽  
Beneficial Microorganisms ◽  
Series Of Experiments ◽  
The Subject

Since 1850, aphids have been regarded as harboring, in mycetomes, supposedly beneficial microorganisms which have, however, been the subject of some controversy. In the present study of the aphids Aphis jabae and Macrosiphum pisi, mycetomes were identified in histological sections; but it proved impossible to isolate or culture any mycetomal microorganisms. Moreover, in a series of experiments in which great attention was paid to refined aseptic techniques no microorganisms could be isolated from the general body cavities or alimentary tracts of the aphids, though simultaneous attempts to isolate microorganisms from weevils were successful.

Research of the activity and viability of spermatozoa at different concentrations and proportions of diluents after incubation

2020 ◽  
pp. 88-95
Author(s):  
Svitlana Lobchenko ◽  
Tetiana Husar ◽  
Viktor Lobchenko
Keyword(s):  
Plasma Concentration ◽  
Incubation Time ◽  
Coefficient Of Variation ◽  
Incubation Medium ◽  
Wide Range ◽  
Series Of Experiments ◽  
The Subject ◽  
Boar Spermatozoa ◽  
Native Plasma ◽  
Better Than

The results of studies of the viability of spermatozoa with different incubation time at different concentrations and using different diluents are highlighted in the article. (Un) concentrated spermatozoa were diluented: 1) with their native plasma; 2) medium 199; 3) a mixture of equal volumes of plasma and medium 199. The experiment was designed to generate experimental samples with spermatozoa concentrations prepared according to the method, namely: 0.2; 0.1; 0.05; 0.025 billion / ml. The sperm was evaluated after 2, 4, 6 and 8 hours. The perspective of such a study is significant and makes it possible to research various aspects of the subject in a wide range. In this regard, a series of experiments were conducted in this area. The data obtained are statistically processed and allow us to highlight the results that relate to each stage of the study. In particular, in this article it was found out some regularities between the viability of sperm, the type of diluent and the rate of rarefaction, as evidenced by the data presented in the tables. As a result of sperm incubation, the viability of spermatozoa remains at least the highest trend when sperm are diluted to a concentration of 0.1 billion / ml, regardless of the type of diluent used. To maintain the viability of sperm using this concentration of medium 199 is not better than its native plasma, and its mixture with an equal volume of plasma through any length of time incubation of such sperm. Most often it is at this concentration of sperm that their viability is characterized by the lowest coefficient of variation, regardless of the type of diluent used, which may indicate the greatest stability of the result under these conditions. The viability of spermatozoa with a concentration of 0.1 billion / ml is statistically significantly reduced only after 6 or even 8 hours of incubation. If the sperm are incubated for only 2 hours, regardless of the type of diluent used, the sperm concentrations tested do not affect the viability of the sperm. Key words: boar, spermatozoa, sperm plasma, concentration, incubation, medium 199, activity, viability, rarefaction.

scholarly journals XIV. On the absorption of gases by solids

1881 ◽  
Vol 32 (212-215) ◽  
pp. 407-408
Keyword(s):  
Royal Society ◽  
Hydraulic Press ◽  
Careful Examination ◽  
Solid Matter ◽  
Chemical Action ◽  
High Pressure And Temperature ◽  
Solid Iron ◽  
Series Of Experiments ◽  
The Subject ◽  
Very High

During the progress of the investigations which I have from time to time had the honour of bringing under the notice of the Royal Society, I have again and again noticed the apparent disappearance of gases inclosed in vessels of various materials when the disappearance could not be accounted for upon the assumption of ordinary leakage. After a careful examination of the subject I found that the solids absorbed or dissolved the gases, giving rise to a striking example of the fixation of a gas in a solid without chemical action. In carrying out that most troublesome investigation, the crystalline separation of carbon from its compounds, the tubes used for experiment have been in nine cases out of ten found to be empty on opening them, and in most cases a careful testing by hydraulic press showed no leakage. The gases seemed to go through the solid iron, although it was 2 inches thick. A series of experiments with various linings were tried. The tube was electro-plated with copper, silver, and gold, but with no greater success. Siliceous linings were tried fusible enamels and glass—but still the' tubes refused to hold the contents. Out of thirty-four experiments made since my last results were published, only four contained any liquid or condensed gaseous matter after the furnacing. I became convinced that the solid matter at the very high pressure and temperature used must be pervious to gases.

scholarly journals XXIX. An account of some experiments to measure the velocity of electricity and the duration of electric light

1834 ◽  
Vol 124 ◽  
pp. 583-591 ◽  
Keyword(s):  
Electric Machine ◽  
Angular Motion ◽  
Continuous Line ◽  
Rapid Motion ◽  
Royal Institution ◽  
Series Of Experiments ◽  
The Subject ◽  
Electric Light ◽  
Rotatory Motion

The path of a luminous or an illuminated point in rapid motion, it is well known, appears as a continuous line, in consequence of the after duration of the visual im­pression. There is nothing, however, in the appearance of such a line by which the eye can determine either the direction or the velocity of the motion which generates it. It occurred to me some years since, that if the motion which described the line in these cases were to be compounded with another motion, the direction and velocity of which were known, it would be easy, from an inspection of the resultant straight or curved line, to determine the velocity and direction of the former. Following up this idea, I made a series of experiments relating to the oscillatory motions of sono­rous bodies, too numerous, and not sufficiently connected with the subject of the pre­sent communication, to be detailed in this place. The satisfactory results thus ob­tained made me desirous to ascertain whether, by similar means, some information might not be gained respecting the direction and velocity of the electric spark : the method by which I then proposed to effect this purpose was first announced in a lec­ture delivered by Dr. Faraday at the Royal Institution in June, 1830. My attention was again drawn to the subject at the commencement of last year, and I attempted to realize the idea in the following manner. Fig. 1 represents the apparatus employed, which was screwed at a to the spindle of a whirling machine, so that a rapid rotatory motion might be given to it. The upper and lower parts, which were all of brass except the wooden disc b c , were insulated from each other by a stout glass rod d e ; a slip of tinfoil connected the ball h with a , and the upper ball g was capable of adjustment to various distances from the lower one h . When the ball f was placed within striking distance of the prime conductor of an electric machine, a spark passed between them, and also between the balls g and h , which could be separated to the distance of four inches, so as to exhibit a spark of that length. It is obvious, that if the angular motion of the balls were in any sensible proportion to the velocity of electricity, there would be a deviation between the upper and lower terminations of the line. The instrument revolving from left to right, if the motion of the spark be downwards, the deflection of the line should be as in fig. 2; and if its motion be upwards, it should be deflected as in fig. 3.

scholarly journals LXI. An account of the phænomena of elec­tricity in vacuo, with some observations thereupon

1752 ◽  
Vol 47 ◽  
pp. 362-376 ◽  
Keyword(s):  
Series Of Experiments ◽  
The Subject

Gentlemen, In a paper I had the honour to lay before you in January 1747, which was the last I communicated to you of my own upon the subject of electricity, and which has been since publish'd in the Philos. Trans , I acquainted you, that I intended upon some future occasion to lay before you a series of experiments in electricity made in vacuo ;

scholarly journals Studies in heredity. I.―The effects of crossing the sea-urchins echinus esculentus and echinocardium cordatum

1911 ◽  
Vol 84 (573) ◽  
pp. 394-403 ◽  
Keyword(s):  
Sea Water ◽  
Sea Urchins ◽  
Female Parent ◽  
Dilute Acid ◽  
Joint Paper ◽  
Echinocardium Cordatum ◽  
Normal Larva ◽  
Series Of Experiments ◽  
The Subject ◽  
The Cross

The manner in which parental characters are transmitted to the offspring when different species of Echinoderms are crossed has been the subject of much experimental enquiry and quite contradictory conclusions have been arrived at by different investigators. Thus Vernon (13), who carried out a most extensive series of experiments with the species of the genera Arbacia, Echinus, Strongylocentrotus, Sphærechinus, and Echinocardium which are available at Naples, came to the conclusion that the condition of the genital glands of the parents (whether imperfectly ripe, fully ripe, or stale) determines in many cases whether or not a hybrid will be formed, and further that though in the majority of cases the hybrid exhibits purely maternal characters, yet it sometimes exhibits paternal characters also, and that this result is also due to the condition of ripeness of the genital glands of its parents. Herbst (5), who also worked at Naples and who used the genera Echinus, Strongylocentrotus, and Sphærechinus for his experiments, found also that the hybrids in many cases showed the paternal influence, but that the extent to which this influence was exhibited varied with the temperature. Doncaster (1), who likewise worked at Naples, also arrived at the conclusion that the greater or less development of paternal characters in the hybrid was due to the temperature. On the other hand, Loeb (7, 8) and his pupil Hagedoorn (4) came to the conclusion that the hybrid exhibited purely maternal characters, and Fischel (2) arrived at the same conclusion on the whole. This conclusion is the more remarkable because Hagedoorn in his experiments used two species of the same genus. Tennent (12) crossed species of the American genera Toxopneustes and Hipponoe and found that the characters of Hipponoe were dominant in the hybrid whichever way the cross was made, but that if the alkalinity of the sea-water were reduced by the addition of dilute acid the influence of Toxopneustes became increased. Lastly Loeb, Redman King, and Moore in a joint paper published quite recently (9), in which they record the results of experiments with the same two species which Hagedoorn used, arrive at the conclusion that the exhibition of paternal and maternal characters in the hybrid is governed by the principle of Mendelian dominance, since, as they assert, the same characters appear in the hybrid whichever way the cross is made, whether, that is to say, in any particular case the character in question is inherited from the male or from the female parent. During a study of the whole subject which I recently made with the object of summarising the present state of our knowledge of this question of the inheritance of paternal and maternal characters in the hybrid, I was struck with the necessity of a preliminary thorough investigation of the characters of the normal larvæ of the species used in hybridisation experiments. The amount of general acquaintance with Echinoderm larvæ displayed by several of the investigators who have attacked the subject is, to say the least, somewhat defective. Thus Herbst (5), who studied chiefly the cross between Sphærechinus and Strongylocentrotus, attaches great importance to the extent to which lattice-work appears in the skeleton of the arms of the hybrid. In the normal larva of Strongylocentrotus, it is true, all four arms are supported by unbranched calcareous rods, whilst in the normal larva of Sphærechinus, each of the two posterior arms is supported by parallel rods connected by cross-pieces like the steps of a ladder, an arrangement which is termed “lattice-work.” But Herbst fails to take into account the fact that in the normal larva of Strongylocentrotus a lattice-work skeleton can appear as a variation, and hence an attempt such as he makes to estimate quantitatively the influence of one parent by the amount of lattice-work which appears in the hybrid rests upon an insecure foundation.

scholarly journals On the measurement of high temperatures

1833 ◽  
Vol 2 ◽  
pp. 331-332
Keyword(s):  
High Temperatures ◽  
Noble Metals ◽  
Pure Gold ◽  
Compensation Principle ◽  
Melting Lead ◽  
Series Of Experiments ◽  
The Subject ◽  
The Many ◽  
The One ◽  
Considerable Depth

The author, after adverting to the many abortive endeavours of former experimentalists to obtain instruments for the accurate ad-measurement of high temperatures, and after suggesting doubts as to the confidence to which Wedgwood’s pyrometer is entitled, describes several attempts of his own to effect this very desirable object. In the course of his inquiries, a remarkable fact presented itself to his notice in the change which occurred in an index constructed on the compensation principle, and formed by two slips of metal, the one of silver and the other of gold, originally quite pure, and united without any alloy. In the course of a few years, although it had never been subjected to a heat above that of melting lead, the whole surface of the gold became converted into an alloy of silver, the impregnation extending gradually to a considerable depth in the gold, and destroying the sensibility of the instrument to changes of temperature. After trying various plans, he gave the preference to one founded on the following principles: namely, that the fusing points of the pure metals are fixed and determined; that those of the three noble metals, namely, silver, gold, and platina, comprehend a very extensive range of temperature; and that between these three fixed points in the scale, as many intermediate ones as may be required may be obtained by alloying the three metals together in different proportions. When such a series of alloys has been once prepared, the heat of any furnace may be expressed by the alloy of least fusibility which it is capable of melting. The determinations afforded by a pyrometer of this kind will, independently of their precision, have the advantage of being identifiable at all times and in all countries: the smallness of the apparatus is an additional recommendation, nothing more being necessary than a little cupel, containing in separate cells the requisite number of pyrometric alloys, each of the size of a pin’s head. The specimens melted in one experiment need only to be flattened under the hammer in order to be again ready for use. For the purpose of concisely registering the results, the author employs a simple decimal method of notation, which at once expresses the nature of the alloy, and its correspondence with the scale of temperature. Thus G. 23 P would denote an alloy of gold with 23 per cent. of platina. As the distance between the points of fusion of silver and of gold is not considerable, the author divides this distance on the scale into ten degrees; obtaining measures of each by a successive addition of 10 per cent. of gold to the silver, the fusion of which, when pure, marks the point of zero; while that of gold is reckoned at ten degrees. If minuter subdivisions were required for particular objects of research, these might easily be made, following always the decimal series. From the point of fusion of pure gold to that of pure platina, the author assumes 100 degrees, adding to the alloy which is to measure each in succession 1 per cent. of platina. Whether these hypothetical degrees represent equable increments of temperature is a question foreign to the purpose of this paper, and must be the subject of future investigation. The author then enters into a detailed account of the method he employed for insuring accuracy in the formation of the requisite series of alloys, and of various experiments undertaken to ascertain their fitness as measures of high temperatures. The determinations of the heats of the different furnaces adapted to particular objects, are given in a tabular form. The remaining portion of the paper contains the recital of the author’s attempts to determine by means of an apparatus connected with an air thermometer, the relation which the fusing point of pure silver bears to the ordinary thermometric scale. An extensive series of experiments, of which the results are given in a table, were made with this apparatus. From the data thus afforded, after making the necessary corrections, the author deduces the following results in degrees of Fahrenheit: viz. A full red heat 1200°; orange heat 1650°; melting point of silver (which had been estimated by Wedgewood at 4717°, and by Daniell at 2233°,) 1830°; of silver alloyed with one tenth gold 1920°. The paper is accompanied with drawings of the apparatus employed.

Paper 24: A Study of Column Separation following Valve Closure in a Pipeline Carrying Aviation Kerosine

1969 ◽  
Vol 184 (7) ◽  
pp. 57-64 ◽  
Author(s):  
J. A. Swaffield
Keyword(s):  
Computer Program ◽  
Method Of Characteristics ◽  
Hyperbolic Partial Differential Equations ◽  
Valve Closure ◽  
Test Rig ◽  
Cavity Collapse ◽  
Upstream Side ◽  
Column Separation ◽  
Series Of Experiments ◽  
The Subject

The occurrence of column separation on the upstream side of a valve following valve closure has been the subject of a series of experiments on a test rig utilizing Concorde L56 alloy fuel piping and Esso Aviation Kerosine Specification 2494. A Fortran IV computer program based on the method of characteristics has been employed to solve the quasi-linear hyperbolic partial differential equations governing the propagation of transient pressures and to predict the duration of vapour cavities formed either at the valve or at any point in the pipeline. Comparison of computer and observed results indicates an accuracy within 3 per cent for the first peak following valve closure and for the duration of the vapour cavities, and within 10 per cent for the later pressure peaks following vapour cavity collapse.

scholarly journals IV. On repulsion resulting from radiation.—Part VI

1879 ◽  
Vol 170 ◽  
pp. 87-134 ◽  
Keyword(s):  
The Other ◽  
General Character ◽  
Experimental Examination ◽  
Present Part ◽  
Series Of Experiments ◽  
The Subject ◽  
Residual Gas ◽  
At Will ◽  
Thin Mica

387. Although the general character of the reactions which cause repulsion under the influence of radiation is now understood, much light may he thrown on the subject by an experimental examination of the direction and strength of the lines of pressure inside the case of a radiometer on which light is allowed to fall. Radiation will pass almost unimpeded through a very thin, colourless and transparent substance such as mica, but molecular pressure or stress is arrested by such a body (232). By introducing fixed or movable screens in various parts of the case of a radiometer, the direction of pressure can be determined at will, and its force can be modified in many ways, whilst all the other conditions of the experiment remain unchanged. In the present Part I propose to give the results of a long series of experiments on the action of thin mica screens in modifying the movements of the fly of a radiometer; I shall examine the action of the residual gas, the action of the sides of the glass case, and the applicability of the information so afforded to the construction of instruments of greatly increased sensitiveness for the purposes of research and illustration; and I shall also describe other experiments which have been tried from time to time during the last few years—experiments which at the time were isolated in their bearings, but which now fit into their places.

scholarly journals Experiments on the restoration of paralysed muscles by means by means of nerve anastomosis

1911 ◽  
Vol 84 (568) ◽  
pp. 75-78
Keyword(s):  
Facial Nerve ◽  
Motor Nerve ◽  
Primary Anastomosis ◽  
Practical Application ◽  
Present Communication ◽  
The Past ◽  
Central Segment ◽  
Nerve Anastomosis ◽  
Series Of Experiments ◽  
The Subject

Restoration of voluntary co-ordinated movements after “nerve crossing,” first demonstrated by Flourens, has since been from time to time the subject of investigation. The conclusions of Flourens have been confirmed by Rawa, Stefani, Howell and Huber, Langley, and myself. A practical application in surgery was first suggested by Letievant, and within the past 12 years considerable development has taken place in this direction. During the past two years I have performed about 30 experiments on monkeys and dogs in order to investigate several points from the physiological standpoint. These experiments fall naturally into three groups. The first deals with the methods of cross union or anastomosis between the peripheral segment of a divided facial nerve and a suitable motor nerve in the neighbourhood. The second series of experiments deals with anastomosis in the fore limb of dogs, in order to investigate some aspects of the question not overtaken by previous work on this part of the subject. The third series deals with the brachial plexus, its functions, and the methods of anastomosis applied to it. The present communication is confined to an account of experiments with the facial nerve, of which there have been 10 performed. Of these 10, 6 were primary anastomosis and 4 secondary anastomosis, that is to say, in 6 the facial was cut, and its peripheral segment immediately anastomosed with the central segment of the substitute nerve, while in 4 the facial was cut, and left unattached for a period, precautions to prevent spontaneous reunion being taken, and then at the end of that period re-exposed, and united to the substitute nerve.

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