Water extraction by the major ampullate duct during silk formation in the spider, Argiope aurantia Lucas

The water, K⁺ and Na⁺ content of naturally produced major ampullate silk as well as silk mechanically drawn from the spider Argiope aurantia have been compared to that of the major ampullate gland. It is demonstrated that water is extracted by the major ampullate duct and that this process is accompanied by an exchange of K⁺ for Na⁺. The significance of these observations is discussed.