A CENSUS OF ELEPHANT AND OTHER LARGE MAMMALS IN THE MKOMAZI REGION OF NORTHERN TANZANIA AND SOUTHERN KENYA

• 1. An attempt has been made to census elephant by a method which will enable the reliability of the results to be assessed.
• 2. The method used was a system of stratified random samples.
• 3. Stratification was based on the positions of elephant clumps recorded on a reconnaissance flight.
• 4. Strip samples were selected at random for the various strata and elephant and other large mammals were counted in a strip of 440 m width from an aircraft travelling 100 m above the ground at 130 km/h.
• 5. The problems of maintaining a fixed height above the ground and counting animals in a strip of constant width are acknowledged.
• 6. One stratum was totally counted for purposes of comparison.
• 7. Elephant, eland, kongoni, Grant's gazelle, buffalo, oryx, zebra, impala, ostrich and giraffe have been counted.
• 8. The results are set out in a series of tables and estimates and confidence intervals have been computed.
• 9. A discussion is held on the influences of various factors on the width of sample strips observed from the aircraft.
• 10. The total count and sample count of stratum 1 are observed to be in fairly close agreement.
• 11. The re-stratification of stratum 1 to take advantage of the observed clumps of elephant reduced the standard error of the estimate proportionally. The estimate was increased because the samples were no longer valid for the new strata.
• 12. The elephant population is of the order of 9,000 animals, as was predicted from observation flights, and the confidence interval of ±1,974 is acceptable for a first attempt at a sample count for elephant. The Mkomazi elephant were observed in three distinguishable groups, this being a distribution pattern frequently recorded since 1965.
• 13. Estimates and confidence intervals for other mammals do not refer to the whole region. It is observed that standard errors as a proportion of estimates are proportional to the degree of clumping shown by the species.
• 14. The census took 45 h, and cost K£800. It was accomplished in 7 d by a single pilot and observer. The Mkomazi region covers some 10,857 km².

     

Reactions of the vaginal plate and the vaginal epithelium to oestradiol monopropionate given once to 5 or 26-day old rats

Summary Five-day old rats were given a single injection of varying amounts of oestradiol monopropionate (OeM) in propylene glycol (0.5, 5, 30 and 150 g) and 26-day old rats were given a single injection of 5 or 150 g OeM. The rats were sacrificed at varying times after the injection and the changes in the vaginal plate and the vaginal epithelium proper were studied. As indicated by the cornification of the epithelium the reaction to OeM is stronger in the vaginal plate than in the vaginal epithelium proper. The response of the vaginal epithelium to 5 or 150 g OeM is most extensive in the rats injected at 26 days of age. With 150 g OeM a cornification of the vaginal epithelium was obtained in rats injected when 26 days old but not in those injected when 5 days old. The reactions in the vaginal plate were compared with those found previously after injections of testosterone propionate. Acknowledgement. This investigation was supported by grants from the Swedish Medical Research Council (12 X-579-03, K67-14X-571-03) and from the Swedish Cancer Society (67:46).     

Dominant inheritance of absence of the breast

Summary A family is described in which congenital absence or hypoplasia of one or both breats was reported in 7 individuals throughout 4 generations. As far as is known, the affected individuals had no other significant anomalies and no evidence of generalized ectodermal dysplasia. Failure of breast development in this family is most likely an autosomal or X-linked dominant disorder.

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Zusammenfassung Es wird eine Familie beschrieben, bei der angeborenes Fehlen oder Hypoplasie einer oder beider Brüste bei 7 Individuen in 4 Generationen beschrieben wurde. Soweit bekannt ist, hatten die befallenen Personen keine anderen bemerkenswerten Anomalien, insbesondere keine Zeichen für eine generalisierte ektodermale Dysplasie. Das Ausbleiben der Brustentwicklung ist in dieser Familie sehr wahrscheinlich autosomal dominant oder x-chromosomal dominant erblich.

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This study was supported in part by Grant 286 from Maternal and Child Health Service, United States Public Health Service.     

The optical function of changes in the medium surrounding the cockroach rhabdom

Summary In the dark-adapted eye of the cockroachPeriplaneta, the fused rhabdom is surrounded by a clear watery palisade; in the light-adapted eye this is replaced by pigment. The refractive indices of the rhabdom and its surround have been measured. The physiological effects of this change in structure has been analysed by the electromagnetic theory of light guides. The optical constants are theoretically consistent with the measured tenfold change in sensitivity and changes in acceptance angle of the retinula cells from 6.7 ° ¦(dark-adapted) to 2.4 ° (light-adapted).     

Can an individual bee ommatidium detect an image?

Summary Even if the dioptric apparatus of the worker bee provided a crisp image at the entrance to the rhabdom, the detection of this image is theoretically impossible due to a phenomenon of mode propagation analogous to acoustic beating or interference.Queen Elizabeth II Research Fellow.We thank Professor G. A. Horridge and Simon Laughlin for their assistance with this study.     

A Three-Dimensional Analytical (Rheological) Model of the Human Left Ventricle in Passive-Active States: Nontraumatic Determination of the In Vivo Values of the Rheological Parameters

In this paper a three-dimensional continuum model of a mammalian left ventricle is formulated. The stresses in the model satisfy the conditions of zero stress on the outer (epicardial surface-representing) boundary. The strains of the model are obtained from the actual dynamic geometry measurements (obtained from cineangiocardiography). Since the left ventricular muscle is incompressible, the dilatational strain is zero and hence the (three-dimensional) deviatric stress components are related to the corresponding strain components by Maxwell and Voigt rheological model analogues of one-dimensional systems; the parameters of the model are series and parallel elastic (SE, PE) elements and the contractile element (CE) (representing the sarcomere). The incorporation of the rheological features of the cardiac muscle into the three-dimensional constitutive equations (for the three-dimensional continuum model of the left ventricle) is a feature of this paper. A procedure is presented to determine the parameters of the constitutive equations (i.e., the SE, PE, and the parameters of the force-velocity relation for the CE) for the left ventricle of a subject from data on the dimensions and chamber pressure of the left ventricle. The values of these parameters characterize the rheology of the left ventricular muscle of the subject. In order to demonstrate clinical application of the analyses, in vivo data of the subjects' left ventricular pressure and dimensions are obtained, and the analyses are applied to the data to determine (for each subject) the values and characteristics of the elastic elements and CEs.     

Purification of cytochrome b6 A tightly bound protein in chloroplast membranes

Purification of cytochrome b₆ was pursued to further develop rational technology for purification, proof of purity, and study of properties of membrane proteins. Cytochrome b₆ was purified—the first time from any source—from spinach chloroplast membranes; yield of pure cytochrome b₆ was 30% of that found in ethanol-extracted particles. The three-step procedure (pH 8) employed: (I) extraction in Triton X-100-4 M (optionally 2 M) urea, (II) chromatography in a Bio-Gel A-1.5m Column (Triton X-100-4 M urea). Without this step, subsequent electrophoresis failed. (III) Preparative disc gel electrophoresis.

Properties of cytochrome b₆: Cytochrome b₆ migrated in undenatured form as a single band in disc electrophoresis (pH 8, 7 or 8.9). None of the limited, accepted properties of the cytochrome in particles was altered by the purification procedure: Reduced b₆ has absorption maxima (22 °C) at 434, 536, and 563 nm; at −199 °C the a absorption region shows two peaks of equal intensity at 561 and 557 nm. Cytochrome b₆ is reduced by dithionite (not by ascorbate) and is autoxidizable. The prosthetic group of b₆ is protohaemin and is fully extractable by acid-acetone. No non-haem iron is present. The millimolar extinction coefficient of reduced b₆ (563–600nm) per mole of haem is 21. The protein equivalent weight is 40000 g per mole of haem. Cytochrome b₄ is an intrinsically aggregatable molecule. The reduced cytochrome does not react with CO except when Triton X-100 is present.     

Eye movements of monkeys during learning of color and form discrimination problems involving reversal and nonreversal shifts

Eye movements of monkeys were measured during performance on a series of two-choice color and form discriminations which involved reversal and nonreversal shifts. Neither the amount of visual scanning nor the duration of individual fixations was related to the relevant dimension or to the type of shift. However, amount of scanning increased over the series of problems and was linearly related to the time to respond. The last fixation of a trial tended to be on the positive stimulus and a fixation near the end of a trial tended to be longer than one near the beginning.This research was supported by a research grant (GB-18953X) from the National Science Foundation to the first author. Part of the research served as the basis for the second author's doctoral dissertation (Vaughan, 1970).     

A Simple Flow Indicator for Use in Perfusion Fixation

In perfusion fixation, we have preferred gravity flow rather than a peristaltic forced flow because the latter may cause rupture of small blood vessels. One difficulty encountered in the gravity flow method is detection of flow stoppage, often caused by the formation of a blood clot. If this is apparent soon enough, steps can be taken to re-establish the flow, Flow stoppage is not usually detected for several minutes—resulting in poor fixation of the organ involved. To allow immediate detection of stoppage, a glass flow indicator (figure 1) was manufactured