Über die Blütenbildung von Kalanchoë Blossfeldiana in verschiedenen Licht-Dunkel-Rhythmen

Ohne ZusammenfassungMit 17 Textabbildungen.     

The skull attributed to Mozart—craniosynostosis or not?

The results of a detailed morphological analysis of the skull attributed to Mozart are presented which refute a recent claim that the skull as well as several of Mozart's portraits show indications of uncomplicated trigonocephaly. These indications according to the present analysis are within the limits of normal variation and derive from retention of part of the long arm of the anterior fontanelle.     

Experimente zur Analyse der Regulationsfähigkeit der frühen Gastrula von Triton,zugleich ein Beitrag zum Problem der Cyclopie

Ohne Zusammenfassung     

Dosage effect study of the microsporidian Octosporea muscaedomesticae in the adult black blowfly Phormia regina,with reference to the reproductive cycle of the pathogen

The quantitative pathogenicity of the microsporidian Octosporea muscaedomesticae in adult Phormia regina was studied. Dosage levels ranging from 10² to 10⁶ spores per fly were administered to five and six groups of newly emerged, starved adult flies in two trials. Rates of mortality and infection were determined. A direct relationship between number of spores ingested and subsequent infection rate was found in a 4-day trial while no such relationship was found in an 18-day trial, using the same source of inoculum and host flies from the same colony. The lack of a direct relationship between spore dose and rate of infection in the 18-day trial is explained on the basis of the short spore-to-spore development time of the parasite. New generations of spores formed within the host tissues obscure the results in relation to the spore dose initially administered. An appreciable number of spores in the inoculum is needed to initiate frank infection. The ID₅₀ (median infective dose) was 4.4 × 10⁴ spores per fly after 4 days.     

TEMPERATURE AND CRITICAL ILLUMINATION FOR REACTION TO FLICKERING LIGHT : I. ANAX LARVAE

The curve of mean critical illumination (I_m) for response to flicker as a function of flicker frequency (F) for the larvae of the dragonfly Anax junius is progressively shifted toward higher intensities the lower the temperature. The maximum flicker frequency (one half the cycle time of light and no light) and the maximum intensity with which it is associated are very little if at all affected by change of temperature. These facts are in agreement with the requirements of the conception that recognition of critical illumination for reaction to flicker involves and depends upon a kind of intensity discrimination, namely between the effects of flashes and the after effects of these flashes during the intervals of no light. The shift of the F-I_m curve with change of temperature is quite inconsistent with the stationary state conception of the determination of the shape of the curve. The dispersion (P.E. _II1) of the measurements of I ₁ is directly proportional to I_m, but the factor of proportionality is less at high and at low temperature than at an intermediate temperature; the scatter of the values of P.E. _II1 is also a function of the temperature. These facts can also be shown to be concordant with the intensity discrimination basis for marginal recognition of flicker.