An automatic soil-washing apparatus for fungal isolation

Summary An apparatus for serial washing of soil particles is described. When forest humus was washed 50 times in an illustrative experiment, the proportion of dark and slow-growing mycelia among fungal isolates was increased from 5 to over 50 per cent.     

An apparatus for anesthetizing small laboratory animals.

A simple apparatus was designed for simultaneous general anesthesia of a number of small laboratory animals with spontaneous respiration. Anesthesia is consistent over many hr. The apparatus consists of an oxygen tank and vaporizer, a glass distribution bottle, and a non-return circuit of separate inspiratory and expiratory valves for each animal. The equipment is inexpensive to construct and can be rapidly adjusted for exact control of gas flow and anesthetic depth.     

Motricity of the female genital apparatus in mammals. Hormonal correlations]

The motility and the pharmacological reactivity of the uterine tract of mammals are linked with the ovarian cycle and the gestation. In the birds, the study of general scheme of the hormonal mechanism and the uterine motility involued in the ovulation, the egg formation and the uterine dilatation can be used as an experimental model of the mammalian gestation.     

The age of olfactory cues functioning in chemocommunication among male domestic cats

In a simulated open-field situation we tried to obtain information about the ability of tomcats to distinguish between urine marks of differing ages. Reactions to these marks were sniffing, sniffing intensively and “Flehmen”. The variables we chose to demonstrate a possible discriminatory ability between urine marks of different ages were: (1) latency, i.e. the time that elapses between the cat's release in the observation arena and the finding of a urine mark, (2) the number of occurrences of Flehmen after sniffing, (3) the frequency of sniffing and Flehmen, (4) the duration of the first sniffing bout and (5) the occurrence of a return to the same scent source during an observation.Our most striking observation was that fresh urine marks (maximum age, 4 hours) were explored first, before marks more than one day old; the other variables did not differ dramatically although we observed a general decline in the intensity of the reaction with increasing age of the urine marks.We also found that the visual characteristics of a urine mark play an important role, particularly in the occurrence of returns. Furthermore we found that the reactions of sniffing and Flehmen are linked with an attempt to identify the donor.All results, including the possible influence upon marking behaviour of the presence or absence of fresh marks, are discussed in the light of the use of a “time plan” spacing mechanism by the domestic tomcat as had been suggested in earlier literature.     

An automatic apparatus for the study of enzyme kinetics

A continuous-flow apparatus is described for automatically plotting substrate saturation curves, and is suitable for use with a variety of enzymes. A linear concentration gradient of the variable substrate is combined with a fixed proportion of the other substrates and the enzyme, and after passing through a reaction coil the product concentrations are measured spectrophotometrically. Use of a 4cm. flow cell and modified spectrophotometer permits accurate measurement of NADH concentration in the region of 0.1mum. Precise control over reaction times and substrate concentration is achieved by using power-driven syringes with an integral mixer. Specimen results are given for yeast alcohol dehydrogenase.     

An automatic, closed-circuit oxygen consumption apparatus for small animals.

An apparatus suitable for the continuous measurement of oxygen consumption of rats and mice is described. The system uses a motorized syringe dispenser to deliver fixed volumes of oxygen to a closed animal chamber. The dispenser is controlled by a micro-differential pressure switch to maintain chamber pressure slightly above ambient. The rate of oxygen consumption is determined by timing the interval between successive operations of the dispenser. The system has proved suitable for a range of experimental conditions and treatments.