PRIMITIVE NERVOUS SYSTEMS

Primitive Nervous Systems.

For nearly fifty years the dominant and accepted theory of the evolution of the nervous system has been that of G. H. Parker, developed over the course of the decade from 1909 to 1919 and summarized in his now classic book The Elementary Nervous System.' Like many successful theories, it was an oversimplification of contemporary knowledge presented in a forceful and stimulating manner. In essen...

Primitive nervous systems: electrophysiology of the pharynx of the polyclad flatworm, Enchiridium punctatum.

1. Electrical activity accompanying motor activity can be recorded from the excised pharynx of Enchiridium punctatum. Multiple stimuli elicit behaviour which consists of an initial aperture closure followed by extension and then peristalsis. If the stimulus parameters are increased the preparation bends from side to side instead of proceeding through the behavioural sequence. Bending appears to...

Central nervous system primitive neuroectodermal tumors: still a useful classification?

Nervous systems

scientist is now being determined by the name of the journals you publish in. Not the contents of the paper, quality of the research or thought, or even the amount of influence the work ends up having, just the impact factor. The electronic revolution could enable scientists to be freer in the form they publish in and the way they discuss their work. You would think this would lead to a broaden...

On Maximal Primitive Fixing Systems

Let max (M) denote the maximal number of points forming a primitive xing system for a convex body M R n. Sharpening results of B. Bollobb as with respect to the quantity max (M) for n 3, we construct counterexamples to the conjecture max (M) 2(2 n ? 1) of L. Danzer. These counterexamples M satisfy max (M) = 1, and they can belong to the following classes of convex bodies: cap bodies, zonoids, a...