The defendant may contest, in writing, the answer of the garnishee, and may allege that the garnishee is indebted to him in a larger sum than he has admitted, or that he holds property of his not admitted by the answer, and shall specify in what particular the answer is untrue or defective. Thereupon an issue shall be made up and tried; but the plaintiff may take judgment for the sum admitted by the garnishee, or for the condemnation of the property admitted to be in his hands, notwithstanding the contest.