“ This Court has frequently emphasized that 'legislative reapportionment is primarily a matter for legislative consideration and determination, and . . . judicial relief becomes appropriate only when a legislature fails to reapportion according to federal constitutional requisites in a timely fashion after having had an adequate opportunity to do so.' Reynolds v. ”

“ Appellants now challenge the constitutionality of the court's plan, contending that a total variance of 18.9% between the largest and smallest Senate district and one of 19.7% between the largest and smallest House district require that the court's districting plan be voided, a new plan instituted, and new elections held. ”

“ The prospective validity of the plan for the 1975 elections, absent legislative action, poses different issues, but we need not decide those questions at the present time. Under the District Court plan, approximately one-fifth of the seats in both Houses were filled by at-large elections from temporary countywide districts in 1971. ”