The problem with the species problem

When Charles Darwin convinced the scientific community that species evolve, the long-held essentialist view of each species as fixed was rejected and a clear conceptual understanding of the term was lost. For the next century, a real species problem existed that became culturally entrenched within the scientific community. Although largely solved decades ago, the species problem remains entrenched today due to a suite of factors. Most of the factors that help maintain its perceived intractability have been revealed and logically dismissed; yet this is not widely known so those factors continue to be influential. It is time to recognize this false foundation and relegate the species problem to history.     

The brachycephalisation problem, a nutrition constitutional problem?

A hypothesis is framed about which any influences of the nutrition may cause variations of the cranium, but concerning physiological data, kinds of nutrition and special victuals' ingredients cannot still be mentioned. If such connexions are proved, at last the well known brachycephalization among European populations since the Middle Ages and the beginning debrachycephalization in the present time could partially be interpreted.     

The Saphirella problem

The problem — one of an assemblage of small planktonic copepods with mixed larval and adult characteristics — is reviewed. It is suggested that some forms are poecilostomatoid first copepodids which have failed to find the definitive milieu and so are unable to moult further. This indicates a need for experimental work. The known species are summarised.     

A diffusion problem

When two polished metal spheres in contact with each other are immersed in a corrosive solution, their surfaces gradually corrode, leaving, however, a non-corroded zone around the point of contact. The size of this zone is a function of the size of the spheres, concentration of the corrosive, and of the time. The phenomenon has been first observed by F. C. Besic on human teeth immersed in hydrochloric acid, and studied on metal balls. In the present paper it is shown that such a phenomenon may be due to gradients of concentration of the corrosive in the neighborhood of the point of contact, caused by the chemical reaction which consumes the corrosive. Approximate expressions for the size of the uncorroded zones as a function of the size of the balls and as a function of time are derived and found to be in fair agreement with F. C. Besic's data.