Some observations on mating behaviour of several cranes in captivity

Responding to the actions of the mate and taking somewhat fixed patterns,Grus japonensis, G. vipio, G. antigone, Anthropoides paradisea andBalearica regulorum pairs are finally led to copulation by a sequence of mating behaviours. There are slight differences in pre-copulatory behaviour patterns between the species and the female's ‘wing-spreading’, being the soliciting and key posture for copulation, differs between the genera; The female's wings are spread wide inGrus, fairly wide inAnthropoides, and are almost folded inBalearica. Post-copulatory behaviours, however, have definite species-specific characters. They usually consist of ‘head-down’ (bowing) or ‘warping’, ‘arching’, etc. immediately following the dismounting of the male inGrus. But a pair ofBalearica first keep their heads high, or gaze at each other for a while, and then show remarkable ‘ruffle-bowing’. These characteristic post-copulatory behaviours are obviously correlated with the threat displays, evolved under agonistic situations, typical to each species.     

Correlation analysis in studying the mechanism of action of smooth muscle stimulants]

The presence of correlation between the value of the maximal effects of acetylcholine and other cholinomimetics, as well as serotonin, barium chloride and depolarizing solution was studied on an isolated strip of rat stomach. It was shown that the effect of acetylcholine closely correlated with the effects of other cholinomimetics, to a lesser degree with the effects of barium chloride and depolarizing solution, and least of all with the effect of serotonin. It is proposed to use the degree of this correlation to analyze the point of action of different drugs and processes of coupling the receptor stimulation with the observed effect. It was shown that the point of convergence of the ways of coupling of the three latter influences preceded the convergence of their common way with the way of coupling of the cholinomimetic effects.     

Some observations on caffeine-induced contracture of barnacle muscle fibers

Isometric tension measurements carried out on uncannulated, intact barnacle muscle fibers show that the minimal concentration of caffeine which produces contracture is 2mM and that which produces maximal tension is 30mM. Pretreatment of barnacle fibers with 3mM-caffeine renders these fibers less sensitive to a second challege e.g. with 30mM-caffeine, the amplitude of the contractile response being time-dependent. Caffeine-treated fibers fail to relax completely. Isotonic tension measurements indicate that the residual tension caused by caffeine is dose-dependent. Significantly, the tension caused by caffeine is independent of the external Ca²⁺.     

Some observations on the intercalated disc of a rat cardiac muscle.

During the experimental investigations special attention was paid to the orthomorphology of the ultrastructure of cardiac muscle intercalated disc in a rat. The contact junction between the cellular membranes of adjacent cells and intercellular spaces are typical for the cardiac muscle intercalated disc. Attention was paid to the three zone system of the junctions, namely: 1. nexus (zonula occludens), 2. fascia adherens (zonula adherens) and 3. macula adherens (similar to the desmosome). Apart from this the cell membranes adjacent to the cells may form digital indentations. A single injection of adrenaline in a dose of 2.4 mg/kg causes sinuate widenings of the intercellular space, but only in the zone of the fascia adherens. The structure of the nexuses and maculae adherentes is unchanged during this time.     

Some observations on the mode of division of somatic nuclei of Mucor and Allomyces

Summary A series of successive photographs of the division of the living nucleus in a germinating sporangiospore of Mucor fragilis has been obtained. In this sequence the nucleus is seen to divide directly by elongation and constriction. The nucleolus divides at the same time and in the same way. These observations agree with the finding, first made by Léger (1896) and several times confirmed since then, that the nuclei of Mucorales apparently divide without first arranging their chromosomes in a metaphase plate and without the help of a spindle apparatus.In stained preparations of Mucor chromosomes are not normally visible as separate entities but they can be clearly seen in Feulgen preparations of dividing somatic nuclei of Allomyces arbuscula. In contrast to Mucor the nucleolus of Allomyces is dissolved during division. The chromosomes seem to sort themselves out on their own and form new nucleoli. Metaphase plates and spindles have not been encountered.To Professor Dr. E. G. Pringsheim, teacher and friend, on his 80th bithday.