The demonstration of Spirochaeta pallida in the electron microscope can be accomplished only after the organisms have been completely immobilized, centrifugated and subjected to repeated washing. Centrifugation and washing are necessary to free the organisms as far as possible from organic material, crystals and other foreign minutiae which interfere with the clear observation of the organism.
The extreme fragility of Spirochaeta pallida, and its rapid immobilization and disintegration under conditions of desiccation, would therefore seem to make its demonstration in the electron microscope a procedure of great technical difficulty.
We have, however, succeeded in demonstrating these organisms in every case examined even under the adverse conditions mentioned. The cases from which specimens have been secured have all been fresh untreated cases of syphilis. Material has been examined from both chancres and secondary lesions. In each case the syphilitic lesion has been repeatedly washed with isotonic solution of sodium chloride. The