On the basis of these findings we believe that we are Justified in saying that the immune serum of Weil's disease is capable of destroying the spirochetes found within the organs in man, with the exception of the kidneys, and that the action of the serum upon the spirochetes is spirochetolytic and spirocheticidal. The scattered spirochetes in the kidney, on the other hand, are resistant to the action of the immune serum.
The spirochetes disappear almost completely from the organs during the convalescent stage of Well's disease, even when no serum has been administered. The only organ to be excepted is again the kidney, but no comparison between .serum-treated and non-serum-treated cases should be made in this respect, for spirochetes are found numerously in the kidneys even with serum treatment.
The disappearance of the spirochetes from the organs and tissues in Well's disease seems to be not so marked with the subcutaneous serum treatment as with the intravenous method, but the manner of their disappearance is about the same.