Greetings! You are correct in assuming the name C. Lemke represents a photographer working in Wausau, WI in the 1880s. The Lemke studio was one of the first in the area and I have pictures of some of my relatives taken in his studio at that time. For more information about him, you may wish to consult a book which I believe is titled: "An Early History of Marathon County, Wisconsin" by Louis Marchetti published ca. 1913? The book may be available by contacting the Jahnke Bookstore in Wausau, WI. It may be possible to borrow it by interlibrary loan also. If you have more information about the various branches of the Lemke family, I would appreciate knowing what you have since I am researching one branch for my own family history. Thanks!