The relationship between Trichuris trichiura (Linnaeus 1758) of man and Trichuris suis (Schrank 1788) of the pig.

Studies were made on the relationship between Trichuris suis of the pig and T trichiura of man. Comparative morphological and developmental studies revealed differences in sizes of the eggs and infective first stage larvae, in the rate of development to the infective larval stage and in development within young pigs following experimental infection. Successful cross infections of man with T suis ova and of pigs with T trichiura ova were achieved for the first time. T suis eggs recovered from one human experimental infection were used to produce a patent infection in a pig. It is argued that while the successful cross infections suggest a close evolutionary link, the differences in morphology, exogenous and endogenous development provide sufficient criteria for the two parasites to be maintained as separate species.     

The hen's egg: Density of egg shell and egg contents

One hundred eggs were used, from hens of seven widely differing strains: two commercial brown‐egg hybrids (one British, one American), two commercial white‐egg hybrids (one British, one Canadian), one broiler strain, one highly inbred strain of laboratory White Leghorns and one laboratory strain of Brown Leghorns. The volume occupied by the shell of each egg was estimated from its surface area—itself estimated by means of a three‐parameter model (Carter, 1968)— and its mean thickness, measured with an anvil micrometer. The volume occupied by the egg contents was estimated by subtracting the shell volume from the egg volume, which was also estimated by means of the three‐parameter model. Mean overall shell density (counting as “shell” all mineral matter and spaces between the outer surface of the mineral shell and a surface through the tips of the mammillae) was estimated, by regressing shell weight on shell volume, to be 2.241 ±0.004 g./cm.³; covariance analysis showed that the strains were homogeneous in this respect. Mean incremental shell density (i.e. the density of shell distal to the mammillary region) was estimated, by regressing shell weight per unit surface area on shell thickness, to be 2.386±0.004 g./cm.³; the strains were homogeneous in this respect too. The mean depth of the intermammillary spaces was estimated to be 19.9 μ. All the residual deviation from the common regression line can be attributed to measurement error. The estimated density of incremental shell is lower than that of calcite; the packing fraction of the crystals in the shell aggregate and/or the atoms in the crystals was estimated to be 92.8 per cent. The density of the egg contents (at the temperature of the bird) was estimated by regressing weight of contents on volume of contents; covariance analysis revealed significant differences between strains, one of the brown‐egg hybrids having the highest density of egg contents, 1.045 g/cm.³, and the laboratory Brown Leghorns the lowest, 1.033; both commercial white‐egg hybrid strains gave a value of 1.040 g./cm.³.     

Influence of food availability,plant productivity,and indigenous forest use on ranging behavior of the endangered samango monkey (Cercopithecus albogularis schwarzi), in the Soutpansberg Mountains,South Africa

Understanding the determinants of ranging patterns in species susceptible to habitat fragmentation is fundamental for assessing their long‐term adaptability to an increasingly human‐dominated landscape. The aim of this study was to determine and compare the influence of ground‐based food availability, remotely sensed plant productivity, and indigenous forest use on the ranging patterns of the endangered samango monkey (Cercopithecus albogularis schwarzi). We collected monthly ranging data on two habituated samango monkey groups, from February 2012 to December 2016, from our field site in the Soutpansberg Mountains, South Africa. We used linear mixed models to explore how food availability, plant productivity, and indigenous forest use influenced monthly ranging patterns, while controlling for group size, number of sample days and day length. We found that as more areas of high plant productivity (derived from remotely sensed EVI) were incorporated into the ranging area, both total and core monthly ranging areas decreased. In addition, both total ranging area and mean monthly daily path length decreased as more indigenous forest was incorporated into the ranging area. However, we found no effect of either ground‐based food availability or remotely sensed plant productivity on ranging patterns. Our findings demonstrate the behavioral flexibility in samango monkey ranging, as samangos can utilize matrix habitat during periods of low productivity but are ultimately dependent on access to indigenous forest patches. In addition, we highlight the potential of using remotely sensed areas of high plant productivity to predict ranging patterns in a small ranging, forest‐dwelling guenon, over ground‐based estimates of food availability.     

The fine structure of the pores in the shell of the hen's egg

1. No fibrous or crystalline material was present in the lumen of pore canals which were exposed by radial fracture and examined with a scanning electron microscope.

2. The walls of the canals were rough, but they did not have a characteristic ultrastructure.

3. The campanulate outer orifice of the pores was plugged with cuticle in which radial cracks formed channels through which the respiratory gases presumably diffuse.     

The outer membrane of the avian egg shell as a reticular structure

The shell membranes of fowl, duck, quail and turkey eggs were examined by electron microscopy. A proportion of the outer membrane fibres from all sources were interconnected by lamellae about 90 A thick. The lamellae, which are probably protein, endow the outer membrane with a secondary reticulum reinforcing the reticulum formed by the fibres themselves.     

The hen's egg: Estimation of shell superficial area and egg volume,using measurements of fresh egg weight and shell length and breadth alone or in combination

1. Shell superficial area (S, mm²) and volume (V, mm³) of an egg can be estimated from any one or a combination of the following measurements: fresh egg weight (W, g), shell length (L, mm) and maximum shell breadth (B, mm).

2. Estimation equations and their error standard deviations are given.

3. The random error of the estimate is smallest when estimation is based on L, B and W together: 0.4% for S and 0.6% for V.

4. Estimation of S based on L and B together has the advantage over that based on W alone that it is unnecessary to measure the egg soon after lay; the random error is the same (0.7%).     

The hen's egg: Relationship between shell thickness and the amount of organic matter in the shell

Percentage weight loss on ashing was measured in 110 shell segments: 4 segments per shell—broad polar cap, narrow polar cap and two halves of the “barrel” —from 28 shells from 4 strains of chicken. The membranes had been removed, by hand, from each shell segment and shell thickness measured with a biconvex anvil micrometer. For each segment the function γ = T (1 + Wodm/Wmdo) was calculated, where T is the mean thickness, Wo the weight loss upon ashing, Wm the ash weight, d0 the density of the organic matter in the shell (assumed to be 1.0075 g/cm3) and dm the density of the mineral matter (2.386 g/cm3). Govariance analysis of the regression of T on T for each shell segment within each strain showed that the regression was linear, that the lines did not differ in slope, but that there were significant differences between the adjusted means for strains and for segments. This is interpreted as demonstrating that (a) the amount of organic matter in incremental shell is constant, estimated at 0.68 per cent by weight, and (b) the amount of organic matter outside incremental shell is variable. The equivalent thickness of the latter was estimated for each segment of each shell with a standard deviation of 0.4 μm. Other evidence suggests that the variation in organic matter outside incremental shell is due mainly to variation in cuticle thickness. Implications for poultry breeding and for future research are discussed.     

Modelling the relationships of egg weight, specific gravity, shell calcium and shell thickness

1. The relationships between egg weight, egg specific gravity, shell weight, shell calcium and shell thickness of 800 eggs from 8 treatments were expressed using mathematical models. 2. The equations describing the relationships were on the basis of any two independent variables predicting the remainder. 3. Of 10 possible models, 4 had high co-efficients of determination (R2 greater than 0.80) for each predicted dependent variable. 4. The two independent variables in each of these 4 models were, in turn, egg weight and specific gravity, egg weight and shell weight, egg weight and shell thickness, and specific gravity and shell weight. 5. The best model was that having egg weight and specific gravity as independent variables, with R2 values of 0.94, 0.88, and 0.85 for predicted shell weight, shell calcium, and shell thickness, respectively. Moreover, egg characteristics can be measured non-destructively by this model, whereas the other three require destruction of the egg.     

Experimental infection in man and monkey (Cercopithecus callitrichus) by sarcosporidian cysts of cattle and swine]

Reported in this paper is experimental sarcosporidial infection of man and lower primates (grass monkey). The courses of infection were followed up by coprological and serological tests. Oral-alimentary administration of 100 Sarcocystis (S.)-fusiformis cysts obtained from cattle muscle caused patent infection in man. Gastro-intestinal symptoms developed in one of the probands, between five and seven days after infection. No sporocysts were detectable from the stools of seven probands who had consumed 200 g each of commercially available minced pork which contained small amounts of Sarcocystis miescherania villi. Rise in antibody to Sarcocystes following infection was detected however, by means of indirect fluorescence antibody reaction (IFAR). Gastrointestinal complaints were reported by one of the probands, one day after infection. No sporocysts were detectable from the stools of four grass monkeys, following oral-alimentary administration of 50 or 25 S. miescherania cysts, but rise in antibody to S. miescherania was recorded in these cases. Those grass monkeys which had received 50 cysts responded by exhibiting, after infection, severe clinical phenomena with intestinal signs and symptoms of the central nervous sytem.     

The influence of handling on egg production,egg shell quality and avoidance behaviour of hens

1. Egg production was similar in non‐handled and in regularly handled hens, but was reduced by handling hens unaccustomed to the procedure.

2. Handling reduced avoidance behaviour (”flightiness“) in growers and pullets but its effect declined with age and it had no influence in these hens when mature.

3. Handling affected egg shell quality; it resulted in an increased incidence of cracks and of equatorial bulges. Previous work has suggested that this defect is an indication of stressors applied at a critical period during egg formation. Therefore, handling may be a stressor.     

The effect of variation in egg numbers,body weight and egg weight upon shell thickness

It is expected that when birds consume a diet with a fixed calcium content variation in the rate of egg production, in body weight or in egg weight will lead to variation in calcium consumption. This analysis investigated whether, in a particular experiment, this also led to variation in egg shell thickness. Data from 67 birds over ten consecutive 28‐d periods were considered. Within birds and within periods it was found that the relationships between shell thickness and these production characters varied at different dietary calcium levels and in some cases the partial regression coefficients calculated were different in sign from those expected. However, only comparatively small amounts of variation in shell thickness could be ascribed to yariation in egg numbers, body weight or egg weight and, after regression, significant (P<0.001) differences still existed in shell thickness between birds. In this investigation there was little tendency for the egg shells to become thinner as the birds aged and hence the correlation coefficients between shell thickness and each of the three production characters due to common seasonal or ageing effects were small. The correlation between the angular transformation of the percentage cracked egg shells produced by each bird and its'mean shell thickness was — 0.357.     

The Hen's egg: Factors affecting the shearing strength of shell material

Experiments are described from which it is concluded that

1. the force required to shear egg shell material can be measured with high precision by pressing a narrow, flat‐ended plunger on to the shell;

2. shearing force falls and the precision of its measurement rises as the radius of the plunger is reduced;

3. shearing force is related linearly to shell thickness ;

4. the regression line of shearing force on shell thickness does not pass through the origin but has a substantial positive intercept on the thickness axis, at about a third of the mean thickness ;

5. there are differences between hens and between strains of hen in the magnitude of the intercept, but not in the slope of the regression;

6. shearing force is affected also by the glossiness of the shell;

7. shearing force was not significantly affected by stripped membrane thickness, number of mammillae per unit area of shell, shell organic content (standardised for shell thickness), shell curvature, shell colour, mottling score, translucent patch score, speckling score, age of the egg or age of the hen that laid it;

8. measured with a plunger of radius 165 μm, the mean shearing strength of incremental shell was 57 kg wt/mm² (3–7 ton/in²).

The findings suggest that the shearing strength of egg shells might be increased by direct selection and by selection for shell glossiness.     

Trichostrongylus auriculatus n. sp. (Nematoda: Trichostrongylidae) from the steenbok, Raphicerus campestris (Thunberg, 1811)

During a pilot survey of the parasites of some artiodactylids in the Kalahari Gemsbok National Park a new species of Trichostrongylus Looss, 1905 was recovered from the small intestine of a steenbok, Raphicerus campestris (Thunberg, 1811), a gemsbok, Oryx gazella (Linnaeus, 1758), and a red hartebeest, Alcelaphus buselaphus (Pallas, 1766). The male spicules were 0,120-0,148 mm long and an ear-shaped protuberance was present on the shaft of the left spicule. The presence of only a single protuberance is characteristic of the species.     

The occurrence of Contracaecum sp. larvae (Nematoda: Anisakidae) in the catfish Clarias gariepinus (Burchell) from Lake Chivero, Zimbabwe

Clarias gariepinus were collected from Lake Chivero, Zimbabwe, and examined for nematode parasites from November 2000 to May 2002. Of the 202 specimens collected, 42.6% were infected with third-stage larvae of Contracaecum sp. in the body cavity. The intensity of the infection was 1-7 worms per fish (mean intensity = 2.2). Seasonal variation in the prevalence of the parasite was not obvious and there was no significant difference in the prevalence of infection between males and females (chi 2 = 2.228; P > 0.05). No significant relationship between host size and prevalence was established. There was also no significant relationship between intensity and the body condition factor (r = 0.11; P > 0.05). The low parasite prevalence may have been caused by the disruption of the infection cycle since piscivorous birds, which are the final hosts of the parasite, do not feed on C. garieplnus in Lake Chivero.