From Eugene F. A. Obach, Cantor Lectures on Gutta Percha (London: William Trounce, 1898), Figure 11. This image is in the public domain in the United States as its copyright has expired.
BRANCH is an open-access publication 
From Eugene F. A. Obach, Cantor Lectures on Gutta Percha (London: William Trounce, 1898), Figure 11. This image is in the public domain in the United States as its copyright has expired.
BRANCH is an open-access publication