1926 11th and 12th Reports of the Director of Veterinary Education and Research - Part 1, September 1926
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Item Splenectomy in domesticated animals and its sequelae, with special reference to anaplasmosis in sheep(Pretoria : Government Printer and Stationery Office, 1926) De Kock, G.; Quinlan, J.B.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of Agriculture1. A certain percentage of South African sheep kept locally become “carriers” of anaplasma. The course of the disease is evidently of such a mild nature that it has never been identified naturally. 2. When sheep introduced from some other centres in Union are injected with the blood of such carriers, reactions of anaplasmosis are set up. Such a disease, as regards its course, symptoms, and the nature of anaplasma, resembles a mild form of bovine anaplasmosis described by Theiler. The disease was propagated in sheep for eleven generations by means of blood-inoculations. 3. When carriers of ovine anaplasma are splenectomized, grave symptoms of anaplasmosis are set, which in some instances prove fatal. 4. In the same way splenectomy of equines, carriers of nuttallia, was followed by a relapse of nuttalliosis with fatal results. In case of bovines, relapses of anaplasmosis alone, or combined with piroplasmosis and gonderiosis, followed. In the latter instance it was shown that bovines reared locally were not necessarily carriers of anaplasma and piroplasma simultaneously. 5. The reactions of anaplasmosis in splenectomized sheep were protracted over long periods, with remissions from time to time. 6. The blood-changes in the splenectomized infected sheep were associated with a marked oligocythaemia, the appearance of erythroblasts, normoblasts, and jolly-bodies. With reference to the leucocytes, first a neutrophilia was noted, then a monocytosis with erythrophagocytosis and a lymphocytosis developed, and in some instances an eosinophilia. 7. It would appear that the neutrophilia is associated with the operation of splenectomy, the monocytosis with the removal of “degenerated” and “damaged” erythrocytes, the lymphocytes seem to have some association with the return to normal of the erythrocytes, and the eosinophilia seem to stand in some relation to the removal of the spleen. 8. The operation of splenectomy in susceptible equines, bovines, goats, and ovines was carried out with practically no impairment. A transitory polyglobuly and neutrophilia were seen in some of the cases. 9. Susceptible and splenectomized susceptible bovines failed to react to “ovine” anaplasma, nor did such “bovines” become carriers of “ovine” anaplasma. 10. Non-splenectomized local goats could not be infected with “ovine” anaplasma, whereas splenectomized local goats only showed the presence of parasites in the blood after a prolonged incubation period. 11. Susceptible and splenectomized ovines could not become infected with “bovine” anaplasma, nor did such ovines become carriers of “bovine” anaplasma. 12. Anaplasmosis in sheep, except for a few instances where Gonderia ovis was seen, could in no way be connected with a stage in the life-cycle of a piroplasmosis. 13. All attempts made to show that anaplasmosis of sheep was associated with a filterable virus failed. 14. It was shown that anaplasma retained its vitality to infect. susceptible sheep when stored in citrate for one week, three weeks, five weeks, and in one case for nine weeks. 15. No difficulty was experienced in differentiating between “anaplasma” and “jolly-bodies.” 16. The “chromatin-bodies” produced by drugs, like pyrogallic acid, were “jolly-bodies” and associated with an oligocythaemia and had nothing whatsoever to do with “anaplasma.” 17. In view of the results arrived at in this paper, and on account of fatal “relapses of malaria” reported to have occurred in human beings after the removal of the spleen, splenectomy in man ought to be carefully considered when undertaken in malarial regions.Item Physiological plant studies in South Africa Part II : transpiration of grasses and other plants under arid conditions(Pretoria : Government Printer and Stationery Office, 1926) Henrici, M.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of AgricultureFrom the locus of writing this article and the companion paper on “Wilting,” it is impossible to consult the extensive literature on transpiration available in European libraries, and for many points of reference Burgerstein's textbook (1904 and 1920) had to be relied upon. Although a modicum of the most recent literature was procured from Europe, not all journals were available, and in considering the Armoedsvlakte experiments attention must be confined, for the time being at least, to certain recent papers which seem to have a special hearing upon their significance. Iljin (1915 and 1916) and Maximow (1923 and 1924) were probably the first authors who treated the Xerophytic plant from a point of view entirely different to that of the ordinary textbooks. Although the South African data now recorded do not altogether bear out Maximow's views, the experiments themselves were carried out with due regard to his standpoint. Huber (1924), whose excellent critical paper was only published towards the conclusion of the Bechuanaland work, actually points out that results different from Maximow's might possibly be obtained in the extreme drought areas of Africa, but apart from this he subscribes almost completely to the general views of the Russian author. He considers it characteristic of a Xerophyte (p. 49) that it can continue transpiration with open stomata even when the soil is drying out and the atmospheric saturation deficit is large, and that in arid areas it can retain its natural ventilation without danger to its water balance. The reduced transpiration as a distinction from Mesophytes loses its significance (p. 96) when Xerophytic characteristics occur, until finally, in extremely dry soil, it is only the osmotic forces which decide the retention of water balance. The more xeromorphic a plant the less important becomes the absolute saving effected by decreased transpiration. These views of Huber, expressed so recently as last year, render it necessary to emphasize again the totally contradictory behaviour of the flora of Bechuanaland. Not one of the investigated plants is capable of extensive dehydration without vital changes in its metabolism, although these cannot be observed without analysing the plant itself, and may proceed even if the plant can still recover its turgescense through rain. In the area studied, an admirable place for Xerophytes, the only plants which keep the stomata open when the temperature is high, the relative humidity and the soil moisture low, are the grasses. All other plants close their stomata, and some even adopt protective positions. At the end of 1922, after a rainless period of ten months, when the country suggested the appearance of a real desert, Elephantorrhiza, Bouchea, Cassia, and Stachys were found with closed stomata; and the two Leguminosae adopted their characteristic protective positions (photographs in Part I on “Wilting”). Should these plants be refused the name of Xerophyte because they cease assimilation in the drought-stricken soil and desiccated air? Is it not wonderful that under such extreme conditions the plants were able to shoot new leaves, continue the metabolism for a few hours each day, but close their stomata for the rest of the time? During this period, of course, no grasses could be found, but in no sense should they be classed as Xerophytes. Huber emphasizes the fact that different plants by no means employ the same means of protection against drought. In South Africa diminished transpiration plays a relatively dominant role, perhaps because some of the most drought-resistant plants have very thin leaves which cannot stand alternate drying out and recovery. It seems probable, however, that the subterranean parts of all these plants are drought resistant in the sense of Maximow and Huber, and that it is this, together with their high suction force, which enables them to shoot in an extremely dry soil. The grasses, which should be separated altogether from the Xerophytes, do behave somewhat like plants which Maximow includes under that term. They continue, at least to a limited extent, their gaseous metabolism right up to the point at which their continued transpiration of water results in permanent withering. Before this point their metabolism is not reduced to a few specific hours each day, but continues all day long in a disturbed fashion. The nature of the disturbance can of course only be revealed by chemical analysis, in which direction certain data are being now accumulated. When the grasses suffer only temporary wilting they may recover completely after rain, so far as external appearance goes; but their metabolism is not restored to normal at the same rate. It is not known at present, in how far the drying out of the plants in Maximow's experiments affects their metabolism, but from the researches of Iljin (1923) some influence would he expected. It seems that the metabolic consequences of alternate dehydration and recovery will have to be investigated before any definite conclusion can be arrived at, concerning the relative advantages to the plant of a capacity to decrease transpiration, and a capacity to lose water at one period which it can regain at another.Item Necrobacillosis in equines : clinical, pathological, and aetiological studies on an outbreak(Pretoria : Government Printer and Stationery Office, 1926) Quinlan, J.B.; Steck, W.; Robinson, E.M.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of AgricultureThe primary lesions are infected wounds in various parts of the body, most frequently in the extremities, from which, owing to the invasion with virulent necrosis bacilli, necrosis and gangrene and collateral phlegmons develop. Metastases are set in the lungs, and these pulmonary lesions go over to pulmonary and parietal pleura, occasionally to the pericardial pleura. Gangrene and cavern formation sets in in those foci which communicate with the lumen of the bronchial tree. The presence of an increased amount of fluid in thoracic cavity and pericardial sac, even when no inflammatory changes are noted, is probably as much part of the local a defensive reaction in the thoracic cavity as of the general cachectic hydrops. In a few eases a broncho-pneumonia is added to these lesions. The degenerative changes in various internal organs (fatty infiltration of myocard, liver, and kidneys), oligaemia, and emaciation are probably the consequences of a toxaemia, which as far as we can judge would represent the immediate cause of death. In bringing about a cachectic condition the toxaemia was doubtless assisted by the reduced intake of food. Metastatic pulmonary foci of pure necrobacillosis, i.e. foci in which microscopically only the typical filaments are discovered, have a characteristic histological structure. There is a central necrotic focus which differs from the foci found in the liver, etc., of cattle, in that considerable portions are crowded with nuclei and nuclear detritus. The nuclei, which belong to desquamated alveolar epithelial cells and wandering cells, are deformed and arranged in such a way that a picture results which has a superficial resemblance with a spindle cell sarcoma. A thin demarcation zone with mainly polymorphonuclear cellulation separates the necrotic centre from the surrounding lung tissue, which represents a reaction zone with serofibrinous and slight cellular exudation, and with the appearance of large swollen fibroblasts in the interstitium. Bacterial filaments are found in debris in the centre, well preserved and numerous in the periphery of the necrotic focus, and especially numerous, forming thick dense layers, underneath the compact outermost membrane-like layer of the tunica elastica pleurae. An organism closely resembling the B. necrophorus was isolated from foci in the lungs of horses dying from necrotic pneumonia. This organism morphologically was identical with B. necrophorus, but appeared to be more difficult to cultivate. It was not proved that this organism was the cause of the disease with which it was associated, and transmission experiments in horses were not successful, the case, of horse 15752 not having been definitely found to have been a true case of necrotic pneumonia. In small animals the results obtained from inoculation of infected material agree with those obtained with B. necrophorus, with the distinction that guinea-pigs were susceptible as well and showed well-marked lesions. It is probable therefore that the organism belonged to the necrophorus group, but that is was a variation from that species which causes the well-known conditions such as disseminated necrosis of the liver in cattle and foot-rot in sheep.Item Check list of the Muscidae and Oestridae which cause myiasis in man and animals in South Africa(Pretoria : Government Printer and Stationery Office, 1926) Bedford, G.A.H.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of AgricultureItem Krimpsiekte(Pretoria : Government Printer and Stationery Office, 1926) Henning, M.W.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of AgricultureOn reviewing the results of these experiments, there can be little doubt that the plant Cotyledon wallichii Harv. (kandelaar bos or bandjes bos) is at least one of the causes of the disease known as krimpsiekte in the western Karroo. The possibility of the parasitic nature of the disease can be completely ruled out for the following reasons: (1) Neither by inoculation nor by contact was it possible to transmit the disease. (2) In no instance on post-mortem was a parasitic organism found which might suggest a parasitic nature of the condition. (3) By sterilizing the plant, both by boiling and by autoclaving, the virulence of the plant was not appreciably reduced, as would be expected in the case of a parasitic organism. (4) Very large quantities of the meat of krimpsiekte animals were required to be fed to dogs in order to produce symptoms, since the toxin had apparently been considerably diluted as a result of its distribution through the tissues. If the disease were of a parasitic nature, considerably smaller doses would be expected to reproduce the malady. (5) Furthermore, since the toxin of this plant is apparently thermostabile, the meat and organs of a krimpsiekte animal cannot be considered safe for human consumption even after boiling or cooking. This conclusion, it will be observe, is contrary to popular belief.Item Urginea macrocenta (Baker) : its toxic effects on ruminants(Pretoria : Government Printer and Stationery Office, 1926) Mitchell, D.T.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of AgricultureIn South Africa three species of liliaceous plants occur to which the common name of Slangkop (snake head) has been given, all of which have been blamed for many years as a cause of mortality in stock. They are: Urginea burkei (Baker) – Transvaal Slangkop; Urginea macrocentra (Baker) – Natal Slangkop; Ornithoglossum glaucum (Salisb.) – Cape Slangkop. Urginea burkei occurs throughout the greater part of the middle and south-western Transvaal, the north-eastern Free State, and in the northern Cape Province (Kuruman and Bechuanaland). Ornithoglossum glaucum is distributed over the greater part of the Cape Province, being plentiful in the Karoo and Kalahari regions. Urginea macrocentra occurs along the coast-belt of Natal, extending as far south as the Transkeian Territories (Cape). It is also found in the Natal midlands up to altitudes of 3,000 feet. Specimens have been identified from the following areas: Inanda, Qudeni, Karkloof, Claridge, Umvoti District, Ifafa (South Coast).Item Report on the transmission of nagana in the Ntabanana and Mhlatuze settlements, Zululand(Pretoria : Government Printer and Stationery Office, 1926) Bedford, G.A.H.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of AgricultureItem The chlorophyll content of grasses in Bechuanaland(Pretoria : Government Printer and Stationery Office, 1926) Henrici, M.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of Agriculture1. The chlorophyll-content of Bechuanaland grasses is not constant throughout the year, but varies from a very high initial value on young leaves, decreases according to the duration and intensity of drought periods, and increases again after rains. 2. Even during periods of twenty-four hours the chlorophyll-content varies greatly, decreasing from early morning to midday, and increasing again during the ensuing night. Decrease and increase depend upon meteorological factors ot the moment, so that on rainy days the variation lies within a few per cent., but on extremely dry and sunny days may extend to 30 per cent. 3. High nocturnal temperature favours a higher general chlorophyll-content throughout the day. Low nocturnal temperature is associated with low chlorophyll, even although the soil moisture is adequate. In both cases, however, chlorophyll destruction and chlorophyll synthesis are regarded as occurring concurrently, the actual content at any time representing the equilibrium between the two processes. 4. The values found in 1923-24 were higher than those found in 1924-25 owing to differences in nocturnal temperature in the two seasons. In the 1923 growing season the chlorophyll-content of the grasses of the Vryburg District was higher than that of European grasses; in the 1924 season about the same, or rather lower. Since the average chlorophyll-content is different in the two seasons, the data cannot be directly compared. What is termed a low value for 1923 would be high for 1924. Apart from nocturnal temperature, other factors, as yet uninvestigated, may play a role.Item The appearance of Gonderia ovis in the blood of splenectomised sheep(Pretoria : Government Printer and Stationery Office, 1926) De Kock, G.; Quinlan, J.B.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of Agriculture1. Gonderia ovis was noticed in the blood of splenectomized “carriers” of Anaplasma. 2. They were not observed in the blood of non-splenectomized sheep. 3. All transmission experiments to susceptible sheep, and in some instances to splenectomized susceptible sheep, failed. 4. Transmission experiment to a bovine failed, although this bovine was still susceptible to Gonderia mutans. 5. Gonderia ovis in South African sheep, and even in splenectomized sheep, appear to be harmless parasites.Item The life histories of Trichostrongylus instabilis and T. rugatus of sheep in South Africa(Pretoria : Government Printer and Stationery Office, 1926) Monnig, H.O.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of AgricultureExperiments in connection with the following points are in progress, and have been partly completed: (a) Bionomics of the free-living larval stages. (b) The development of the worms in sheep at different seasons. (c) The effects of the parasites on their hosts. (d) The prevention of infection. (e) The treatment of infested sheep.Item Helminthology notes(Pretoria : Government Printer and Stationery Office, 1926) Monnig, H.O.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of AgricultureItem Helminths collected from the domestic fowl (Gallus domesticus) and the domestic pigeon (Columba livia) in Natal(Pretoria : Government Printer and Stationery Office, 1926) Le Roux, P.L.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of Agriculture1. The domestic fowl (Gallus domesticus) in Natal suffers heavily from verminous infestations. 2. Six species of nematodes and nine species of cestodes have been collected from the digestive tract of the fowl. 3. Three species of nematodes and two species of cestodes have been collected from the digestive tract of the domestic pigeon, which may succumb to heavy infestations. 4. D. crassula (Rud., 1819) Fuhrmann has armed suckers. 5. Chickens may he infected with A. sphenoides by feeding infected earthworms to them. 6. Agriolimas aegrestis is a local intermediate host of D. proglotina.Item The anatomy and life history of the fowl tapeworm (Amoebotaenia sphenoides)(Pretoria : Government Printer and Stationery Office, 1926) Monnig, H.O.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of Agriculture(1) Cysticercoids, of which the hooks resemble those of Amoebotaenia sphenoides, were found in earthworms collected in a fowl-run infested with this tapeworm. (2) Earthworms [Ocnerodrilus (Hyogenia) africanus, Beddard, var. nov.] were artificially infected with this cysticercoid by placing them in a hox of foil to which droppings of the infested fowls were added. (3) The development of the cysticercoid was followed by means of a series of stages obtained from artificially infected earthworms. (4) Clean chicks, fed with earthworms containing the cysticercoid, became infected with Amoebotaenia sphenoides, while the controls remained uninfected. (5) The cysticercoid needs about fourteen days for its complete development and the tapeworm about four weeks.Item Cytological studies on heartwater II : Rickettsia ruminantium in the tissues of ticks capable of transmitting the disease(Pretoria : Government Printer and Stationery Office, 1926) Cowdry, E.V.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of AgricultureThe evidence observed in favour of a causative relationship between Rickettsia ruminantium and the production of heartwater falls under the following headings: (1) The discovery of Rickettsia ruminantium in the tissues of goats, sheep, and cattle suffering from heartwater; the close association between their presence in these three species and the febrile reaction; their disappearance soon after the fever has commenced to decline corresponding to the loss in infectivity of the blood; and their absence in control animals (Part 1 of this Report). (2) The appearance of the same Rickettsia, easily identifiable by their very characteristic morphology and staining reactions in two series of ticks (607 and 614) which had fed upon cases of heartwater and which, before feeding, did not contain them; and their non-appearance in three series of control ticks (604, 605, and 606) from the same parent stock which had fed upon normal animals. (3) The fact that the ticks containing Rickettsia in their alimentary tracts when fed upon susceptible animals, produced in them typical attacks of heartwater, which the control ticks, devoid of Rickettsia, failed to do. (4) The completion of the cycle by the recognition of the same Rickettsia in the tissues of these animals (sheep 8049 and goat 9651) which contracted heartwater as a result of having been bitten by the infective ticks containing Rickettsia.Item Cytological studies on heartwater I : the observation of Rickettsia ruminantium on the tissues of infected animals(Pretoria : Government Printer and Stationery Office, 1926) Cowdry, E.V.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of AgricultureA Gram-negative, intracellular, coccus-like micro-organism was found in cases of heartwater in the three species which are susceptible to the disease, namely, goats, sheep, and cattle. The presence of this micro-organism was definitely related to the febrile reaction, and it was absent in controls. It probably occurred throughout the body, but was most easily detected in the renal glomeruli and in the small capillaries of the cerebral cortex. The micro-organism was a typical endothelial parasite, being restricted in distribution to the endothelial cells of the smaller blood-vessels and to portions of them which broke off into the blood stream. It was never observed to cause any injury to the endothelial cells other than mechanical distension through accumulation in large densely packed masses which were characteristically spherical. A typical attribute was the presence of several of these masses with the cytoplasm of a single endothelial cell. In view of the association of this micro-organism with heartwater, which is a disease of ruminants, and thus far the only one in which micro-organisms resembling Rickettsia have been reported, the designation Rickettsia ruminantium is proposed.Item A group of micro-organisms transmitted hereditarily in ticks and apparently unassociated with disease(Pretoria : Government Printer and Stationery Office, 1926) Cowdry, E.V.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of Agriculture1. Pleomorphic, bacterium-like, Gram-negative, intracellular micro-organisms, which stained much less intensely with ordinary dyes than most bacteria, were found in fifteen ticks comprising examples of both the Argasidae and the Leodidae and belonging to the following species: Amblyomma americana, Argas persicus, Boophilus decoloratus, Dermacentor variabilis, Dermacentor venustus, Haemophysalis leachi, Hyalomma aegyptium, Margaropus annulatus, Margaropus annulatus australis, Ornithodorus megnini, Ornithodorus turicata, Rhipicephalus appendiculatus, Rhipicephalus evertsi, Rhipicephalus sanguineus, and Rhipicephalus simus. 2. No morphological or tinctorial evidence could be adduced of injury to the tissues of their arachnid hosts other than physical distension o£ the cells to accommodate them in large numbers. Since microscopic examination of favourable preparations of the species which contained them revealed an incidence of 100 per cent. not only in ticks collected in South Africa, but also in others from Jamaica, Trinidad, Honolulu, and several parts of the United States, it is probable that the micro-organisms were in no sense harmful to their hosts. 3. In consideration of the detection of the micro-organisms in the egg of ten species, in the unfed larvae of seven species, and at very close stages throughout the life-cycle of two others, the conclusion was reached that they were transmitted hereditarily. 4. The micro-organisms in several respects resembled Rickettsia, but differed from them in being of larger size. They also resembled the symbionts of certain lice and blood-feeding flies, but never gave rise to definite organ-like structures comparable with the mycetomes, and were restricted in their distribution to the Malpighian tubules and the egg-cells, as contrasted with the digestive tract to which the symbionts of these insects are confined.Item Notes on the decomposition of diluted polysulphide dips(Pretoria : Government Printer and Stationery Office, 1926) Van Zyl, J.P.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of AgricultureAlthough the recorded work is not comprehensive enough to allow for very definite conclusions, it is indicated that the decomposition of this common scab dip is not so rapid nor of such a nature that the farmer with a small flock (and a small purse) may not use the wash left over from the first dipping for the second dipping as well.Item Contributions to the helminth fauna of South Africa(Pretoria : Government Printer and Stationery Office, 1926) Baer, J.G.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of AgricultureWhereas the South American and Australian helminth-fauna is comparatively well known, that of South Africa has been sadly neglected until recent years. The probable reason of this is that scientific explorers do not generally trouble to collect intestinal parasites either because of the extra trouble incurred, or else underestimating the importance of this factor for faunistic studies. It was with this fact in mind that Sir Arnold Theiler, K.C.M.G., Director of the Veterinary Research Laboratory, Onderstepoort, Pretoria, had collected all the intestinal parasites from the animals shot for museum purposes in the districts outlying Pretoria. This valuable collection, which was presented to Prof. 0. Fuhrmann a few years ago, consists chiefly of nematodes and of avian cestodes, the mammalian cestodes studied in this paper representing about one-quarter of the whole collection. As was to be expected, of the twenty-two species examined, nine are new to science, including two new genera and one new family. Of the nineteen hosts, fifteen have to our knowledge never been recorded before as harbouring cestode parasites. We have been able to clear up certain points of systematic interest. This represents, however, an infinitesimal portion of the work left to be done with regard to mammalian cestodes. Certain genera are in much need of revision: the genus Taenia s. str. is an example. To our mind, only good results are to be obtained from the study of the original species, and any species insufficiently described of which no types or cotypes exist should be suppressed. This seems to be the only way of straightening out the synonymy of certain groups, in which much confusion has been caused of late by "occasional helminthologists," whose only aim seems to be to place their name behind a species. The results of our studies have showed us that authors do not generally take into consideration the individual variation of a species, variation which, as we will show, may be very great in certain cases. The role of the host should also be considered, and would prevent authors committing such absurdities as the recording of species of Anoplocephala, Davainea, and Hymenolepis from marine fishes!Item Remarkable case of volvulus in a calf due to aplasia of the mesentery(Pretoria : Government Printer and Stationery Office, 1926) Steck, W.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of Agriculture(1) A three-month-old bull-calf dies suddenly as a result of a complicated volvulus. (2) This volvulus is due to a reduction of the mesentery (probably congenital) in a part of the small intestine, which allows a part to slip through the loop formed by a torsion of 180 degrees of the neighbouring loop and so to fix that loop.Item Blood studies : a contribution to the study of the blood and circulation in horsesickness(Pretoria : Government Printer and Stationery Office, 1926) Neser, C.P.; Theiler, Arnold, Sir, 1867-1936; Union of South Africa. Department of Agriculture1. In the dikkop form of horse-sickness: (a) sedimentation of red corpuscles is much accelerated in the later stages of the disease, owing to clumping of the cells. This clumping is due to a property acquired by the plasma; (b) at the time of the fever acme and for some time thereafter, the jugular blood becomes poor in red cells, probably mainly on account of the tendency towards clumping and the weak action of the heart. These favour erythrocyte retention in the capillary system. It is possible that water retention and decreased formation of red cells also play some subsidiary part in the production of this phenomenon; (c) the decreased erythrocyte content of venous blood decreases peripheral resistance considerably, and allows the heart to maintain a fairly bulky circulation in spite of mechanical interference with its action (hydropericardium) and weakening of the myocardium; (d) the dyspnoea which is noted in some cases is due not so much to the decreased oxygen carrying capacity of the blood, as to the inability of the heart to maintain a sufficiently bulky circulation and so ensure the efficient removal of wastes; (e) if oedema formation is rapid and extensive and if complications such as paralysis of the oesophagus or pharynx persist for a long time, jugular blood may again become rich in red cells. This increases peripheral resistance and favours sudden cardiac failure. 2. In peracute and very mild cases of horse-sickness no marked or constant changes in erythrocyte content of jugular blood are noted – probably because there is no time for the formation of haemagglutinins, or because these are formed only to a very slight extent. 3. In all cases of horse-sickness, leucocytes disappear progressively from the jugular blood during the incremental stages of the disease; the rate at which leucocytes disappear is an index of the severity of the disease, but the extent of disappearance is to some extent also dependent upon the duration of the disease.