What is Homopolymer, Polyanetholesulfonate?

A compound originally developed as an anticoagulant, but possessing anticomplement action and lowering the bactericidal action of blood. It is used in vitro to inhibit blood coagulation and as a diagnostic reagent to encourage the growth of pathogens in the blood. It is also used to stabilize colloidal solutions such as milk and gelatin. (From Merck Index, 11th ed)