Showing papers by "Commonwealth Scientific and Industrial Research Organisation published in 1970"
TL;DR: A spectroreflectometric technique was used to determine the relative percentages of three myoglobin pigments, reduced myoglobin, oxymyoglobin and metmyoglobin at the surface of fresh beef and it was shown that, at constant humidity, the formation of meetmyoglobin in beef was maximal at 6 + 3 mm Hg of oxygen.
Abstract: SUMMARY: A spectroreflectometric technique was used to determine the relative percentages of three myoglobin pigments, reduced myoglobin, oxymyoglobin and metmyoglobin at the surface of fresh beef. It was shown that, at constant humidity, the formation of metmyoglobin in beef was maximal at 6 + 3 mm Hg of oxygen at 0°C and 7.5 ± 3 mm Hg at 7°C for semitendinosus muscles. Carbon dioxide concentrations of 10% and higher had negligible effect on the formation of metmyoglobin, provided the oxygen pressure was above about 5%. At high partial pressures of carbon dioxide, absorption of carbon dioxide increased and the pH of the surface decreased. In air, the formation of metmyoglobin varied widely from muscle to muscle.
210 citations
TL;DR: Observations on root-hair distribution suggest that developing nodules can suppress further infection by suppressing the emergence of root hairs on newly developing roots.
Abstract: Calcium and hydrogen ions interacted on nodulation. Increasing acidity from pH 5.6 to pH 4.8 increased the calcium concentration required to nodulate 50% of the plants, from 0.1 mM to 6 mM. Calcium concentration below 0.2 mM or pH below 4.8 inhibited nodulation at all tested levels of the other variable. Root extension and root-hair production were insufficiently affected by calcium or pH to explain reductions in nodule numbers.
206 citations
TL;DR: An attempt to account quantitatively for the pulse width, polarization and spectrum of the pulses.
Abstract: An attempt to account quantitatively for the pulse width, polarization and spectrum of the pulses.
170 citations
TL;DR: In this article, the ion exchange properties of low-rank coals have been studied with a view to obtaining optimum conditions for the determination of carboxyl groups in the presence of phenolic groups.
166 citations
TL;DR: In this article, a critical examination of current steady-state one-dimensional cloud models which postulate lateral entrainment is performed and it is found that such models cannot simultaneously predict values of liquid water content and cloud depth which are in agreement with observations.
Abstract: A critical examination is undertaken of current steady-state one-dimensional cloud models which postulate lateral entrainment. It is found that such models cannot simultaneously predict values of liquid water content and cloud depth which are in agreement with observations. If sufficient entrainment is postulated to get agreement with observations of cloud water content, the model cloud does not grow as high as those observed in the given environment, while entrainment appropriate to the observed height yields liquid water contents that are too high. It is suggested that the success claimed for these models is based on a choice of arbitrary constants which may be valid only for a limited range of atmospheric conditions; in other conditions, predictions from the model may be seriously in error. In addition, since the physical basis of these models is invalid, we have no way of knowing what conditions are most important or how to avoid the necessity of selecting fresh constants by trial and error w...
141 citations
TL;DR: The extent to which ammonia-N (NH3-N) serves as a starting point for synthesis of microbial nitrogenous compounds was assessed when 15N as (15NH4)2SO4 was continuously infused into the rumen of a sheep for periods of 78–98 h.
Abstract: 1. The extent to which ammonia-N (NH3-N) serves as a starting point for synthesis of microbial nitrogenous compounds was assessed when 15N as (15NH4)2SO4 was continuously infused into the rumen of a sheep for periods of 78–98 h. Steady states were reached in the composition of the rumen contents because the animal was fed equal parts of its ration at hourly intervals. Concentrations of 15N in bacterial-N, protozoal-N and rumen NH3-N were compared.2. In two trials with a low-N diet consisting largely of wheaten hay the 15N concentration in bacterial N was 76 and 78% of that in the NH3-N. For protozoa the values were more variable —64 and 43%.In two trials with a higher-N diet (lucerne hay), the corresponding values were lower—bacterial-N 62 and 64%, protozoal-N 41 and 35%.It was concluded that synthesis of microbial protein was more dependent on ammonia as a starting point with the low-N diet than with the higher-N diet.3. Entry and exit rates for ammonia into and out of the rumen system were determined, and the results, in combination with those obtained for bacterial-N in the first part of the work, allowed calculations to be made of the production of microbial-N/d formed from NH3-N, and this in turn allowed calculation of minimal values for conversion of plant-N to microbial-N in the lumen. Minimal extent of conversion was 68% for the low-N diet and 53–55% for the higher-N diet.4. Total production of microbial-N in relation to the amount of N given was also calculated by using previously reported values for the relative proportions of protozoal-N and bacterial-N in sheep given diets similar to those used here. These values for extent of conversion were 73% for the low-N diet and 58–59% for the higher-N diet.
128 citations
TL;DR: In this paper, it was shown that superficial scald is caused by the oxidation of α-farnesene and that the control of scald by diphenylamine is due to its antioxidant action.
Abstract: α-Farnesene was oxidised to conjugated trienes with an absorbance maximum at 269 nm and the oxidation was inhibited by diphenylamine both in hexane solution and in the natural coating of stored apples. The results suggest that superficial scald is caused by the oxidation of α-farnesene and that the control of scald by diphenylamine is due to its antioxidant action. The mechanism of scald induction is discussed.
111 citations
TL;DR: It is now firmly established that the substitution of poly-unsaturated fats for saturated fats in human diets will cause a reduction in the concentration of serum cholesterol, and ruminant fats are largely excluded from the diets of patients being treated for coronary heart disease.
Abstract: THERE seems to be a significant relationship between serum cholesterol concentrations and the incidence of atherosclerosis in man1–4. In the past, considerable attention has been focused on the possible relationships between the consumption of ruminant products (for example, lamb, beef, milk, butter, cheese and cream), high concentrations of serum cholesterol and coronary heart disease in man5. These relationships have been attributed largely to the relatively high proportions of saturated fatty acids that occur in ruminant fats, and the possible role of these fatty acids in increasing serum cholesterol concentrations6,7. Moreover, it is now firmly established that the substitution of poly-unsaturated fats for saturated fats in human diets will cause a reduction in the concentration of serum cholesterol5–10. For these reasons, ruminant fats are largely excluded from the diets of patients being treated for coronary heart disease5,11. The availability of poly-unsaturated ruminant products would therefore assist in the formulation of special diets for experimental work and for therapeutic use in patients with atherosclerosis.
82 citations
TL;DR: The authors found that males of D. melanogaster that were confined with a female touched and oriented toward other flies more frequently than did males not exposed to a female and that the odour of males caused some increase in the frequency of touching and orientation behavior among exposed males.
81 citations
TL;DR: Mucus from several species of marine fishes contained up to 20 times more lipid per unit area than human sebum, and analyses revealed free fatty acids which may provide protection against bacterial and fungal attack.
Abstract: Mucus from several species of marine fishes contained up to 20 times more lipid per unit area than human sebum. The analyses revealed free fatty acids which may provide protection against bacterial and fungal attack. Carotenoids were prominent components. The amount of phospholipids present in fish mucus seems to determine its viscosity.
80 citations
TL;DR: The efficiency of production and utilization of vitamin B12 was studied with sheep given a cobalt-deficient diet with and without supplementary Co (1 mg/d), and labelled cobalamin was selectively retained by liver, kidneys and the walls of parts of the alimentary tract.
Abstract: 1. The efficiency of production and utilization of vitamin B12 was studied with sheep given a cobalt-deficient diet with and without supplementary Co (1 mg/d). Vitamin B12 to lignin ratios in rumen contents were used to estimate minimum rates of production and these were related to faecal and urinary excretion. Tissue distribution and excretion of vitamin B12 were studied with [58Co]cyanocobalamin and 5′-deoxyadenosyl[60Co]cobalamin.2. Labelled Co was rapidly sequestered by particulate material in the rumen and was largely excreted in the faeces. Most of the vitamin B12 in whole rumen contents was contained in micro-organisms, but was released on incubation at pH 2. Added cyanocobalamin was partly degraded in the rumen.3. The vitamin B12 to lignin ratio in rumen contents began to decline 1–3 d after cessation of a daily Co drench. Estimated ruminal production of vitamin B12 on full feed was not less than 400–700 μg/d with supplementary Co and 50–110 μg/d from the Co (0.01–0.05 μg/g dry weight) in the basal diet. Production of vitamin B12 appeared to be limited by food intake with or without additional Co.4. At full feed the efficiency of production of vitamin B12 from Co in the basal diet was about 13% while that from added Co was about 3%. Part of the vitamin B12 produced in the rumen was degraded before reaching the faeces and about 5% was absorbed. The minimum total requirements of sheep for vitamin B12 are assessed at about 11 μg/d.5. Injected 5′-deoxyadenosylcobalamin was better retained than injected cyanocobalamin, faecal excretion exceeded urinary excretion with both. Labelled cobalamin was selectively retained by liver (particularly by the mitochondria), kidneys and the walls of parts of the alimentary tract. Vitamin B12 was secreted into the duodenum and reabsorbed in the ileum, but little secretion occurred above the duodenum and little absorption below the small intestine.
TL;DR: In this paper, principal component analysis on the same single-gradient models of vegetation is used to obtain a curve-inear ordination similar to those of Swan (1970) for a single species.
Abstract: Curvilinear ordinations similar to those of Swan (1970) are obtained by using principal component analysis on the same single—gradient models of vegetation. Any non—linear relationships between species will produce such a result.
TL;DR: In this paper, the barium hydroxide exchange procedure for the determination of acidic groups in coals has been re-examined, using a wide range of low-rank coal samples (61.7-79.1% carbon d.m.f. basis).
TL;DR: In this paper, it was shown that artifacts may occur possibly due to complexes of the protein with ampholines with phenomenon has also been demonstrated for some basic proteins and methods for demonstrating the presence of artifactts involve varying the ratio of ampholine to protein, re-runnng of discrete bands, or applying the protein sample at different positions on the gel.
TL;DR: Accumulated evidence seems to suggest that dehydroascorbic acid has a function in the control of mitotic activity.
Abstract: Accumulated evidence seems to suggest that dehydroascorbic acid has a function in the control of mitotic activity.
TL;DR: The first meaningful observation with the 80 MHz Cul-goora radioheliograph was made on 2 September 1967, a few weeks before the instrument was officially commissioned, and the Sun has since been observed on 438 days as mentioned in this paper.
Abstract: The first meaningful observation with the 80 MHz Cul-goora radioheliograph was made on 2 September 1967, a few weeks before the instrument was officially commissioned. Systematic observations, normally for 4 to 6 hours per day, began late in February 1968 and the Sun has since been observed on 438 days. The remaining days and many nights have been used for investigations of radio sources and the interplanetary medium and for maintenance and instrumental extension. The standard of reliability thus achieved has been due to the sustained efforts of K. V. Sheridan, W. J. Payten, K. R. McAlister, M. Beard and their colleagues. These first two years have been a period mainly of exploration—a phase of great interest to those engaged in observing, though possibly bewildering to those not. The present review is a first attempt to collate and summarize what has so far been found and where possible to draw preliminary conclusions. The observations to be described and their discussion have been due to a joint effort on the part of a number of workers, particularly G. A. Dulk (on leave from the University of Colorado), K. Kai (on leave from the University of Tokyo), N. R. Labrum, D. J. McLean, A. C. Riddle, K. V. Sheridan, S. F. Smerd, R. T. Stewart, and the present writer. The period has also seen considerable development in the evolution of intricate computer programmes for analysing the data, particularly on the part of L. H. Heisler and D. J. McLean.
TL;DR: Malathion resistance is recorded from eastern Australia in Tribolium castaneum associated with peanuts and cereals in storage, and the relationship between this response and mortality is discussed in this paper.
TL;DR: It is pointed out that, under certain conditions, it becomes irrelevant whether matches in primitive attributes are included or excluded when reconstructing a cladogram (the branching pattern of a phylogeny) by phenetic methods, and that a phenogram therefore supplies a reasonable phylogenetic hypothesis.
Abstract: Examination of a simple evolutionary model shows that the deficiencies of a phenogram, as an estimate of an historical cladogram, are not as great as sometimes imagined. In reality, there are grounds for a fair degree of confidence, particularly in relationships between taxa of higher rank. It can be shown, for instance, that uniformity in rates of evolution is not critical. What is required is, roughly, that later stocks should not evolve for substantial periods at rates much greater than in earlier stocks and/or that sister-species should diverge appreciably before undergoing further splitting. Likewise, the convergent elements of resemblance need not be small, or even uniform: simply, and roughly, later lines should not converge upon each other less than upon earlier lines. The latter holds also for "phylogenetic" reconstructions, based on what are believed to be resemblances in derived attributes only. There seem to be reasonable grounds for believing that such conditions are often met in Nature, and that a phenogram therefore supplies a reasonable phylogenetic hypothesis, for testing against further characters and taxa (but not methods) as they become available. This analysis does not conflict with the pragmatic aspects of classification, and can supply some criteria for choice of a numerical method; for instance, there are grounds for favouring "average linkage" as a clustering strategy. In a recent note (Colless, 1969), I pointed out that, under certain conditions, it becomes irrelevant whether matches in primitive attributes are included or excluded when reconstructing a cladogram (the branching pattern of a phylogeny) by phenetic methods. I was unable at that time to explore the situation in any detail; in fact, I drew several intuitive conclusions that were incorrect. Since then, Throckmorton (1968) has published an elegant formulation of a quantitative, "phylogenetic"l method; but he, like many other advocates of such methods, proceeds from the basic premise that, for credible reconstruction of a cladogram, primitive attributes must be identified, and as far as possible excluded from the outset. The situation therefore calls for further comment. I must here reiterate a basic thesis (Colless, 1967), which is essentially that of Bader (1958), that a "good" phenetic classification requires only the acceptance of evolution as a fact for it to become a "good" evolutionary classification. Mayr (1968, 1969) and, before him, Ghiselin (1966) 1 My usage of this term, and "phenetic," is d6scribed in Colless (1971). castigate the phenetic approach as based on a misinterpreted, nominalist or operationalist philosophy, which regards taxa as "constructed," rather than "discovered." But that is a straw man-whatever the attitudes proclaimed by some of its proponents, the operations prescribed by phenetic method do not in any way require such a viewpoint. It is perfectly legitimate to describe them as the search for "natural" structure, and to interpret the results as fair estimates of phylogeny (see "Conclusion"). As in so many cases, what really matters is what we do, rather than the philosophy we proclaim while doing it. Throckmorton (1968) adopts the common and perfectly valid attitude that sharing of primitive attributes (Hennig's symplesiomorphy, which term I shall use here) does not constitute evidence of cladistic structure within the group for which they are "primitive." Such matches contribute one element of "cladistic noise"; the other element is contributed by "convergence" (see below) and together they obscure the cladistic "signal." "Noise" is of course being used here in a broad, non-technical sense, to mean interfering, irrelevant signals. A distinctive feature
TL;DR: Of the other cultivars, R had more primordia at all temperatures and light intensities; each cultivar performed well at high temperature and light intensity, but only R performed well under poor conditions.
Abstract: Plants of five cultivars (Sultana, syn. Thompson Seedless; Muscat Gordo Blanco; Rhine Riesling; Shiraz; and Ohanez) of grape-vine (Vitis vinifera L.) were grown for 13 weeks in controlled environment growth cabinets, and then the number of bunch primordia present in buds was counted after dissection. Sultana (S) and Ohanez (0) had very few bunch primordia under all conditions. Of the other cultivars all were barren after growth at 15° C, but Rhine Riesling (R) and Shira". (Sh) had some primordia at 20° C, and Gordo (G) at 25° C. Primordia number of R, Sh and G increased with increase in temperature up to approximately 35° C. R had most at all temperatures. At a light intensity of 900 foot candles (f. c.) R had some primordia, but other cultivars were barren. At 1800 f. c. both R and G had a moderate number of primordia, but Sh was barren. At 3600 f. c. R, G and Sh all had fruitful buds. R had the greatest number of primordia at each intensity. R and Sh had more primordia when 16 hours of light per day were given continuously than when in two portions separated by 4-hour dark periods. S and O produced very few bunch primordia under any of the conditions tested. Evidence is presented that this result was due to a later differentiation of bunch primordia in buds of these cultivars, such that primordia were still unrecognisable at 13 weeks. Of the other cultivars, R had more primordia at all temperatures and light intensities; each cultivar performed well at high temperature and light intensity, but only R performed well under poor conditions.
TL;DR: In this article, the reference level, or level of no horizontal motion, may be at least as deep as 2300 m, instead of 1300 m as assumed previously. But the observed currents were in the range 2-7 cm/sec, and showed no clear evidence of being coherent with surface currents.
TL;DR: In this article, the vertical air velocity in a cumulus cloud of depth ranging from 0.7-4 km was measured, and peak updrafts and downdrafts were found to increase with height above cloud base, the latter at a rate of about 0.5 m sec−1 km−1.
Abstract: Results are given of detailed measurements of vertical air velocity in cumulus clouds of depth ranging from 0.7–4 km. Both peak updrafts and downdrafts and rms vertical velocity were found to increase with height above cloud base, the latter at a rate of about 0.7 m sec−1 km−1. The rms velocity also increased as the stability of the clear air environment of the cloud decreased, at a rate of about 0.3 m sec−1 per °C km−1. Maximum, upper decile and median peak updrafts were 12.7, 10.0 and 4.9 m sec−1, respectively; corresponding values for downdrafts were 9.5, 7.5 and 3.5 m sec−1. The structure obtained by combining measurements of horizontal and vertical air velocity at short intervals throughout a traverse showed well-defined overturning motions near the cloud top but not elsewhere. Power spectra are presented which show that most of the energy is at long wavelengths; peaks are also present at wavelengths of 500–600 m within the body of the cloud, but at 100–200 m near cloud base or cloud top.
TL;DR: In this article, a description of recent high-resolution observations of the sun made at 80 MHz with the Culgoora radioheliograph is given, where it is suggested that the type I storms originate in strong magnetic fields above sunspots while the type III bursts originate in weak magnetic fields outside the strong field regions, possibly in neutral sheets.
Abstract: A description is given of recent high-resolution observations of the sun made at 80 MHz with the Culgoora radioheliograph. In many cases the sources of type I storms show bi-polar structure, the two components being spatially separated by about 3′ arc and strongly circularly polarized in opposite senses. Similar behaviour has been found for stationary type IV bursts which appear indistinguishable from type I storms on the heliographic records. On the other hand the sources of the weakly polarized type III bursts show uni-polar structure. The latter avoid the precise locations of type I sources even when they are associated with the same active centre. It is suggested that the type I storms originate in strong magnetic fields above sunspots while the type III bursts originate in weak magnetic fields outside the strong-field regions, possibly in neutral sheets.
TL;DR: In this paper, the growth mode of ice crystals in natural clouds has been studied by examination of replicas of more than 10,000 crystals sampled in about 120 clouds over the temperature range −2 to −32C.
Abstract: The growth mode of ice crystals in natural clouds has been studied by examination of replicas of more than 10,000 crystals sampled in about 120 clouds over the temperature range −2 to −32C. The relationship between the basic ice crystal form deduced from the shape of recently formed small ice crystals and the temperature at which they have grown is found to agree well with the results of laboratory experiments. Within each category of basic crystal form, there is some characteristic and systematic variation in the ratio of crystal axes which depends strongly upon the growth temperature. The growth of an ice crystal along either the a or c axes almost ceases after it reaches a certain length which depends upon the growth temperature. For columnar ice crystals, the ratio of the length of the c axis to the a axis at a given column length has a maximum value at about −5C. For plane ice crystals, the ratio of diameter to thickness for a given diameter has a maximum value at about −15C. Some considerat...
TL;DR: Action spectra studies indicate that 14C-acetate incorporation into fatty acids follows the absorption spectrum of chloroplasts, and very low concentrations of detergents greatly stimulate 13C- acetate incorporation and markedly increase the oleic to palmitic ratio.
TL;DR: Examination of each of the four phases of systems analysis reveals some of the problems involved in the use of systems methods in ecology.
Abstract: Systems analysis is defined as the use of scientific method with conscious regard for the complexity of the object of study. It has strong relationships with problem solving, in that the same four phases–lexical, parsing, modelling, and analysis–are identifiable in both. Examination of each of these phases reveals some of the problems involved in the use of systems methods in ecology. A model of a precipitation—evaporation system is presented as an example. Problems in experimenting with models of systems and with control, optimization, and comparison of such models are considered. See full-text article at JSTOR
TL;DR: In this paper, equine herpesviruses (EH viruses) were isolated from 9 horses in three separate outbreaks of respiratory disease, and evidence was presented that some of the horses were ill, possibly as a result of recurrent infection, and that reactivation of a persistent, latent infection may have occurred.
Abstract: Summary
Equine herpesviruses (EH viruses) were isolated from 9 horses in three separate outbreaks of respiratory disease. The pattern of disease in the three stables is described and evidence is presented that some of the horses were ill, possibly as a result of recurrent infection, and that reactivation of a persistent, latent infection may have occurred. An ulcerative condition of the pharyngeal region was seen in some of the horses with EH virus infection.
The cytopathogenicity for equine foetal kidney cells of the 9 EH viruses varied considerably. One isolate, EH 39 virus, which was recovered from an acute, upper respiratory tract infection, was rapidly cytopathic for equine foetal kidney cell cultures and was shown in neutralisation tests to be identical with, or closely related to equine rhinopneumonitis virus (EH virus type 1) that is associated with acute respiratory disease and abortion in other countries. More slowly cytopathic isolates were recovered from mild to subclinical upper respiratory tract infections. Evidence is presented that the property of slow cytopathogenicity is probably related to the tendency of these viruses to remain cell associated. Slowly cytopathic isolates were recovered from the nasal cavity of horse 89 on two occasions 79 days apart. One of the eight slowly cytopathic isolates, EH 86 virus, was shown to be antigenically distinct from equine rhinopneumonitis virus (EH 39 virus).
TL;DR: Equations describing diffusion of the isotopic species in the solid phase are not relevant here because phosphate ions react only with the Fe(111) ions exposed at the goethite surfaces, and no measurable diffusion of phosphate ions into the bulk of the crystals was observed.
Abstract: FE(111) phosphate complexes are formed on the surfaces of goethite (α-FeOOH) crystals suspended in dilute aqueous orthophosphate solutions The rates of isotopic exchange reactions, in which phosphate ligands on the crystal surface exchange with free phosphate ions from the surrounding solution, can be readily measured by conventional techniques, using a small quantity of 32P-labelled orthophosphate solution added to the equilibrium suspension No satisfactory method is, however, available to interpret kinetic data for isotopic exchange in heterogeneous systems (two phases) Equations describing diffusion of the isotopic species in the solid phase, used when the extent of fast surface-exchanging reactions is small compared with the amount of the slower diffusion-controlled exchange involving the bulk of the solid1–3, are not relevant here because phosphate ions react only with the Fe(111) ions exposed at the goethite surfaces No measurable diffusion of phosphate ions into the bulk of the crystals was observed
TL;DR: Phospholipid production was severely inhibited in cycloheximide-treated cells, but the production of galactolipids showed the same pattern as that of chlorophyll, a lag phase followed by a period of accelerated synthesis.
TL;DR: In this article, the EH 39 virus type 1 (EH 39 virus; equine rhinopneumonitis virus) was found to be slowly cytopathic for equine foetal kidney cell cultures and serologically unrelated to the inoculated EH39 virus.
Abstract: Summary
An 8-month-old filly (No. 2) developed an acute vulvo-vaginitis and respiratory disease following inoculation of equine herpesvirus (EH virus) type 1 (EH 39 virus; equine rhinopneumonitis virus) into the vestibule of the vagina. The same virus produced acute respiratory disease but not balanoposthitis following intranasal, intravenous and intrapreputial inoculation of a 12-month-old colt (No. 3). A second 8-month-old filly (No. 1) developed a mild respiratory disease but not vulvo-vaginitis following intravestibular inoculation of EH 39 virus. EH viruses that were slowly cytopathic for equine foetal kidney cell cultures and serologically unrelated to the inoculated EH 39 virus were isolated from the buffy coat cells at 3 days and from the nasal cavity at 6 days after inoculation of horse No. 1.
EH virus that was slowly cytopathic and serologically unrelated to EH 39 virus was isolated at 16 days from the vagina of the filly (No. 2) that developed acute vulvovaginitis and was frequently isolated from the nasal cavities of 2 of the 3 horses for 83 days and from the nasal cavity of the third horse for 57 days under conditions that precluded reinfection from other equidae except from each other. EH viruses were recovered from the 3 horses for a further 58 days under conditions where contact with other equidae may, although was not known to, have occurred between 83 and 141 days postinoculation.
It was concluded that these viruses represented a single virus type that was present in the nasal cavity (designated EH 1–6 virus) perhaps also the blood stream of filly No. 1 at the time the 3 horses were purchased and that this virus was subsequently transmitted to the vagina of 1 and the nasal cavities of the other 2 horses. Accordingly a carrier state for EH 39 virus was not shown to occur. These findings are discussed in relation to the natural history of EH virus infections.
Attempts to reactivate the EH viruses to cause clinical respiratory disease, by a series of injections of adrenalin and cortisone, were inconclusive. The 3 horses showed no clinical evidence of respiratory disease when they were reinfected intranasally with EH 39 virus 360 days (1 horse) and 412 days (2 horses) after the initial infection with this virus.
Abortion was produced when EH 39 virus was inoculated directly into the allantoic or amniotic cavity of a pregnant mare although naturally occurring EH virus abortion remains unrecognised in Australia.