LS (the body written in the hand of Darwin’s son), four pages on two adjoining sheets, 5 x 8, Down, Beckenham, Kent letterhead, January 3, 1878. Darwin writes to an unnamed gentleman. In part: “Your letter has interested me greatly. Dr. Sanderson [British physiologist John Scott Burdon-Sanderson, 1828–1905, who undertook research on the relationship of microorganisms to disease] showed me some admirable photographs on glass by Dr. Koch [German physician and future Nobel Prize winner Robert Koch, 1843–1910, who pioneered the field of microbiology] of the organisms which cause splenic fever; but your letter & the valuable work which you kindly gave me make the case much clearer to me. I well remember saying to myself between 20 & 30 years ago, that if ever the origin of any infectious disease could be proved, it would be the greatest triumph to science & now I rejoice to have seen the triumph. With respect to the filaments of Dipsacus, I do not for a minute put my judgement on a par with yours of that of deBary, but my son has lately made some observations which incline me very strongly to believe the filaments consist of living matter of the nature protoplasm. Hearing from Dr. Sanderson, that thymol has a fatal effect on low organisms, he tried solutions ... which cause contractions of the filaments. On the other hand, 1/2% solution of carbolic acid does not cause contraction, 1/10% does so. This agrees with several observers who find, I believe, that 1/2% carbolic solution is not poisonous (F. microzumes). My son finds that strong solutions of NaCl cause contractions but not death as the filaments recover themselves in water & do not swell up into bladders as they do after poison. This agrees with deVries’ work on the ‘plasmalysis’ of cells....” As Darwin was at this stage of his career involved mainly with botanical research—he would later observe that he spent “the whole of this last year [1878] ... on the circumnutating Movements of plants & bloom”—the content of the present letter, related to the emerging field of microbiology, which would soon revolutionize the understanding and treatment of infectious diseases, is highly unusual and significant. Accompanied by an unsigned carte-de-visite photo. Faint show-through of ink, and a few tiny stray ink spots to final page, otherwise very fine, fresh condition. Auction LOA John Reznikoff/PSA/DNA and R&R COA.
