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Data from 14 stocking rate experiments, conducted over the period 1964-72, are used to derive a general relationship between wool production (W, kg sheep-1) and stocking rate (R, sheep ha-1), for the wool-growing areas of Victoria. This relationship is: W = (2.10 + 1.11P - 0.0045 C2) - (0.16 + 0.026 P - 0.00054 C2). R, where P ('productivity', kg sheep-1) and C ('carrying capacity', sheep ha-1) characterise any particular locality in a given year. The relationship is shown to be in accord with a simple theoretical model. In addition, some comparative ewe-wether relationships are presented.

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Three approximate non-linear parameter estimation algorithms are investigated numerically in the suboptimal control of a jacketed CSTR with perfect measurements. Depending upon the initial estimates and the noise covarianee, the algorithms may or may not be stable. A limiting analysis in a noise-free environment is developed to expose possible singularities. In this case the Bayesian-normal approach leads to serious instabilities.

Many chemical processes are characterized by significant process disturbances, but negligible measurement noise. By combining the state and measurement equations, and considering the parameter drift equation to be the new ' state ' equation, parameter estimation algorithms in the presence of feedback control can be developed. A Bayesian approach is used herein to develop the estimate of a parameter appearing linearly in a non-linear state equation.

The present study constitutes an attempt to correlate the processes of insect metamorphosis with certain of the more obvious metabolic changes characteristic of larval and pupal life. Throughout this work it has become obvious that the chemical constitution of different batches of larvae or pupae may be very different although all composed of individuals of the same age. One particular instance of this may be cited at the outset. Two batches of larvae, A and B, were reared under almost identical conditions, A being from slightly earlier ovipositions and reaching maturity about two days before B. Both were reared at a somewhat low temperature until nearly mature and the only differences between the two batches were that the higher temperature would commence nearer maturity for batch A than for batch B, and that the sand in which A were reared was somewhat more moist than was the case for larvae B. Both batches pupated very slowly. In each case samples of the body fluid were taken on the day when the majority of the larvae had evacuated the gut, and again two days later. Not only was there marked differences in the physical properties of the body fluids but there was also a difference in colour: the fluid of specimens A being yellow and deeply pigmented, whereas that of B had the normal greenish tinge and was less pigmented.

1. The resting nuclei of Cucurbita pepo and Cucurbita maxima contain a single, spherical nucleolus that is relatively very large. Part, at least, of this nucleolus persists during nearly the entire process of mitosis. During the metaphase it lies in the equatorial plate and becomes elongated in the direction of the long axis of the spindle, to form first a cylinder and then, with further elongation, a dumb-bell-shaped structure, which finally separates into two fragments that migrate to the opposite poles of the spindle. This entire movement occurs prior to any anaphase migration of the chromosomes. The nucleolar fragments apparently are not included in the daughter nuclei during the telophasic reconstruction, but degenerate in the cytoplasm. 2. Examination of the literature suggests that a similar process of nucleolar division probably occurs in a wide variety of plant-cells. 3. The bearing of this type of nucleolar division on theories of the dynamics of anaphase migration of the chromosomes is briefly discussed.

This paper investigates the use of the fast Fourier transform as an aid in the analysis and classification of spectroscopic data. The pattern obtained after transformation is viewed as a weighted average and/or as a frequency representation of the original spectroscopic data. In pattern recognition the Fourier transform allows a different (i.e., a frequency) representation of the data which may prove more amenable to linear separation according to various categories of the patterns. The averaging property means that the information in each dimension of the original pattern is distributed over all dimensions in the pattern resulting from the Fourier transformation. Hence the arbitrary omission or loss of data points in the Fourier spectrum has less effect on the original spectrum. This property is exploited for reducing the dimensionality of the Fourier data so as to minimize data storage requirements and the time required for development of pattern classifiers for categorization of the data. Examples of applications are drawn from low resolution mass spectrometry.

In vitro tissue culture is shown to be a possible mode of experimentation with the tissues of the Blow Fly larva. Methods are described-whereby the tissues, and the body fluids requisite as culture media may be obtained free from bacteria. The imperfections of the technique are noted and the conclusion reached that a successful technique must depend on the rearing of bacteria-free larvae, for which a method is briefly outlined. It is shown that progress in this part of the work must await further physiological knowledge, particularly in respect to the nature of the body fluids.

The females of Pseudococcus maritimus have three types of multicellular wax-glands, one with a triangular external pore, another opening through a long tube, and a third with a multilocular aperture. The first two are widely distributed on all surfaces of the adult. The third is restricted to the ventral surfaces of the last five segments. This multiloeular type is found only in the adult. The triangular glands are found at all stages and these structures progressively increase in number with each successive instar. The tubular type appears first in the second instar; the number is reduced in the third instar; and in the adult it is again increased to the largest number found at any stage. The three glands are all modifications of one general plan of histological structure. The glandular elements are sub-epidermal cells arranged in a ring of peripheral cells surrounding a single central cell. There are three peripheral cells in the triangular gland and ten in each of the others. The peripheral cells are uninucleate and contain vacuoles of secretory material. The central cell of the tubular and triangular glands has a large and two small nuclei and contains a large reservoir, from which a chitinized duct system leads to the gland-pore. The central cell of the multilocular gland is small and relatively undifferentiated. The author favours the view of Šulc that the wax is probably secreted by the peripheral cells, while the central cell secretes a substance that causes the wax filaments to adhere to form large cylinders. The glands are developed by cell-multiplication from the epidermis at the time when it is freed from the cuticula at the beginning of ecdysis. After the initial period of cell-multiplication the first differentiation is the development of the external pore within the neck-cell. Later in the development of multilocular glands it is believed the glandular cells grow through the neck-cell to establish the functional relationship with the pore. It is suggested that this is analogous to the relationship between tormogen cell and trichogen cell in the development of a spine.

A modification of Broughton's method for the determination of barbiturate in biological fluids is described which reduces the time of analysis to 15 min. and requires only 2 ml blood. Minimal reagents and apparatus are required. The method has been standardised and is accurate to barbiturate concentrations as low as 0.5 mg/100 ml blood.

1. A series of one hundred consecutive cases of trochanteric fractures treated conservatively by the authors has been reviewed.2. Analysis of the results obtained and a study of the relevant literature has led us to the firm conclusion that the routine treatment of this group of fractures should be conservative.3. Internal fixation should be reserved for those exceptional cases where traction is found to be inadequate: this is specially likely in cases associated with an upper motor neuron lesion, where difficulty is experienced in maintaining reduction owing to muscle spasm.4. The basal type of fracture offers a special problem because it merges imperceptibly into that of the true transcervical fracture. No difficulty has been experienced in this series in the conservative treatment of such fractures, but we recognise that they might well be regarded as a variety of transcervical fracture and treated by nailing in order to avoid the risk of non-union.