The middle ear of the skull of birds The Procellariiformes

Much emphasis has been placed on the middle ear region of reptiles and mammals as a taxonomic character. However, the anatomy of the middle ear region of birds has yet to be described adequately. The literature on the middle ear of birds is reviewed briefly and then the osteology and soft anatomy of the middle ear region of the skull are described for the families of the avian order Procellariiformes. Particular emphasis is paid to the foramina and paths of the nerves and blood vessels. Also discussed is the morphology of the basicranium and the quadrate. Comparative analyses of the characters are used to assess taxonomic conclusions.     

The Law of the Lifegivers: The Domestication of Desire

The Law of the Lifegivers: The Domestication of Desire. René Devisch and Claude Brodeur. Langhorne, PA: Harwood Academic Publishers, 1999. 268 pp.     

The Vascularization of the Anuran Brain: The Mesencephalon

The angioarchitecture of the toad's mesencephalon is studied by scanning electron microscopy of vascular corrosion casts. The arterial supply is performed by the superior mesencephalic artery and by an artery arising from the ramus posterior of the arteria carotis cerebralis just in front of the retroin-fundibular communicating artery. The venous drainage is exerted by the vena diencephalica, the vena lateralis mesencephalis and by anterior and posterior branches of the encephaloposthypophysial portal vein. Characteristics of the mesencephalic angioarchitecture are the centrifugal direction of the blood flow, the intensive capillarization, and the formation of vascular meshworks in the region of the stratum griseum periventriculare tecti and of the stratum griseum superficiale tecti.     

The hippocampus: The shock of the new.

Recent successes in functional brain imaging have suggested that the hippocampus is part of a novelty-detection network; but consideration of the available evidence and of the cognitive demands of novelty processing suggests that things are not so simple.     

The CNS syndrome. The characteristics of the intermediate filaments of the rat brain

A study was made of the effect of ionizing radiation on the content and polypeptide composition of filamentous and soluble glial fibrillary acidic protein (GFAP) in different regions of rat brain. Ionizing radiation was shown to decrease considerably the level of soluble GFAP in cerebral cortex, cerebellum, middle brain and hippocampus. Polypeptide composition of soluble GFAP detected by the immunoblot method was found to be changed considerably in different brain areas of irradiated animals.     

The Mechanism of the Gram Reaction I. The Specificity of the Primary Dye

Dyes of all major types were tested for their suitability as the primary dye in the Gram stain. When a counterstain was not used, some dyes of all types were found to differentiate Gram-positive from Gram-negative organisms. When a counterstain was used, these dyes were found to vary greatly in their suitability. Those dyes found to be good substitutes for crystal violet were: Brilliant green, malachite green, basic fuchsin, ethyl violet, Hoffmann's violet, methyl violet B, and Victoria blue R. All are basic triphenylmethane dyes. Acid dyes were generally not suitable. Differences in the reaction of Gram-positive and Gram-negative cells to Gram staining without the use of iodine were observed and discussed but a practical differentiation could not be achieved in this manner. Certain broad aspects of the chemical mechanism of dyes in the gram stain are discussed.     

The evolution of the development

The evolution of development required few new features not already present in the eukaryotic cell, as exemplified by the cell cycle. Moreover, the protozoa possess many features of spatial organization and regulation present in metazoan embryos.
The earliest multicellular organism could have been reproduced by a stem cell mechanism or by fission, the latter requiring cell-to-cell interactions that may have favoured cell-interactions and regulation. Regeneration can be considered as a meta-phenomenon related to asexual reproduction and retention of embryonic characters. The origin of embryonic structures like the gastrula may be accounted for in terms of Haeckel's 'Gastrea' theory. Mechanisms based on selection at the level of cell lineage are rejected.
It is not clear what selective forces act on development itself, as distinct from the requirement for reliably producing a functional orgainsm. There is, for example, a major problem why gastrulation should be so variable in related animals. Selection for rate of development in relation to energy utilization may play a role. If many variants are neutral this may facilitate the evolution of novelty.
In general terms there is a requirement for a continuity principle for the evolution of each form in development. Most groups pass through a phylotypic stage with considerable diversity before and after.