J Exp Med. 1917 Jan 1;25(1):45-64.
Ishiwara K1, Ohtawara T, Tamura K.
QUOTE- "In the original animals spirochetes were seen chiefly toward the end of the process and the conditions as to the period previous to it are not yet clearly known. In further generations of all the animals we used, spirochetes were found in the peripheral blood 4 or 5 days after inoculation, and gradually multiplied until the greates number was reached about the 10th day after inoculation. They then began to decrease; yet spirochetes could be observed over 2 months later. 7. We have found spirochetes chiefly in the adrenals of the animals by Levaditi's method, but have not yet ascertained their distribution in other organs."
Link Here- https://www.ncbi.nlm.nih.gov/pubmed/19868078