Abstract: Implantable surgical articles are provided which are at least partially bioresorbable and which consist at least partially of a copolyester of succinic acid and oxalic acid possessing receiving units of the general formulae: ##STR1## in which each R radical in the chain, which may be identical or different, represents a linear or branched alkylene radical possessing 2 to 6 carbon atoms, at least 2 of which carbon atoms form part of the polymer chain, a cyclo-alkylene radical possessing 5 to 8 carbon atoms, or a radical of the general formula: ##STR2## in which each of R.sub.1 and R.sub.2, which may be identical or different, represents a methylene or ethylene radical. They are particularly suitable as sutures.

Abstract: Four component polymerization initiators for olefinic monomers comprise (1) an oxidizing agent such as hydrogen peroxide, a persulphate, a permanganate, a chlorate, a perchlorate, a bichromate, a bromate, a ceric salt, an oxazirane, an organic peroxide or an organic hydroperoxide, (2) a chelate compound of a metal such as titanium, iron, vanadium, aluminum, tin, manganese, chromium, cobalt, copper, zinc or bismuth in which the metal is not fully coordinated, (3) an electron donor in amount at most equal to that required to complex completely the said metal of the chelate compound, the said electron donor being for example an amine, a monoalcohol, an ether, an aldehyde, a ketone, an imine, an oxime, an amide, a sulphonamide, or a phosphonamide, and (4) a chelate complex or salt which is different from the chelate compound (2) and in which the metal may be for example, copper, iron, magnesium, manganese, chromium, vanadium or tin, the degree of coordination of the said metal being different from that of the met