Let k be a differential field of characteristic 0, and Ω be a universal extension of k. Suppose that the field of constants k0 of k is algebraically closed. Consider the following differential polynomial of the first order over k in a single indeterminate y: T(y) = (y′)2 - λS (y; k) λ ∈ k; λ ≠ 0; here S(y; k) = y(1 - y)(1 - κ2y); κ ∈ k; k2 ≠ 0, 1; k′ = 0. Take a generic point z of the general solution of T. Then, z is transcendental over k, and k(z, z′) is called a differential elliptic function field. We prove the following: THEOREM. Let k(z, z′) be a differential elliptic function field over k. Then, there exists a finitely generated differential extension field k* of k such that the following three conditions are satisfied: (i) z is transcendental over k*; (ii) the field of constants of k* is the same as k0; (iii) there exists an element ζ of Ω such that k*(z, z′) = k*(ζ, ζ′) and (ζ′)2 = 4S(ζ; κ) with the same modulus as κ.
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