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SEVERAL discoveries over the past 15 years have progressively led to the recent suggestion that metals of low work function (high in the electromotive series) would not thrombose on implantation into the aorta or vena cava when used as a prosthetic vessel replacement. A series of experiments based on the above hypothesis has recently been completed. The results appear to confirm the postulate which may now, perhaps, be dignified by the term "theory."Historically, several of the more important experiments which led to the hypothesis were:1. Abramson's classical experiments in 1927 to 1942 in which he quantitated the electrophoretic characteristics of blood cells of several mammalia and showed that these all had a negatively charged surface and moved toward the positive pole in an electrophoresis apparatus.1,22. The discovery that with onset of thrombosis the normal polarity of an electrode pair, placed across blood vessel wall, reversed. Normally,

The physiology of the gut movements in invertebrates has been little studied. In the case of the earthworm, although numerous investigations have been published on the physiology of locomotion and of the neuro-muscular structures of the body wall, nothing has yet appeared on the gut movements. It was with the intention of throwing light on this problem that the present investigation was undertaken.

In the course of a recently published investigation (Wu, 1939) it was found that the gut of the earthworm differed from the well-known preparation of the dorsal musculature of the leech (Fühner, 1918; Minz, 1932), as regards its reactions to acetylcholine, in the following respects: (1) in the absence of eserine the body wall of the leech is very much less sensitive to acetylcholine than is the gut (crop and gizzard) of the earthworm, the lowest effective concentration of the drug being 10−4 to 10−5 for the former and 10−5 to 10−10 for the latter; (2) treatment with eserine increases the sensitivity to acetylcholine of the leech dorsum enormously and that of the earthworm gut only slightly, so that the former (lowest effective concentration 10−8 to 10−10) is now nearly as sensitive as the latter (10−10 to 10−10); (3) adopting the classification of Dale (1914), the action of acetylcholine on the leech is a “nicotine-action” (abolished by large doses of nicotine) while that on the earthworm gut is a “muscarine-action’’ (abolished by small doses of atropine). The question therefore arises, are these differences due to the fact that we are dealing with two species, earthworm and leech, or with two organs, body wall and gut? To answer this question, the writer has studied the action of acetylcholine and certain other relevant drugs on the body wall of the earthworm (Lumbricus terrestris) and of the lugworm (Arenicola marina). By putting these results beside those already established for the leech, a comparison can be drawn between the reactions of the body wall in representatives of all of the three great divisions of the annelid phylum. As regards the gut, the data of Wu (1939) on the earthworm and of Wells (1937) on the lugworm are also available for comparison.