Koch's De­vel­op­ment of Early In­sta­Gram Pos­i­tive Pho­tog­ra­phy

by Daniel P. Haeusser

Robert Koch is one of the key fig­ures in early bac­te­ri­ol­ogy, help­ing de­velop cul­ture tech­niques (e.g. solid me­dia), crit­i­cal rea­son­ing (e.g. Koch's pos­tu­lates), and dis­ease eti­ol­ogy (e.g. cholera and tu­ber­cu­lo­sis). He also pub­lished the first pho­tomi­cro­graphs of bac­te­ria (Fig­ure 1A) in his 1877 pa­per Ver­fahren zur Un­ter­suchung, zum Con­servieren und Pho­tographiren der Bak­te­rien.

Fig­ure 1A. Koch's pho­to­graph of B. an­thracis, one of sev­eral pho­tomi­cro­graphs in his 1877 pa­per, the ear­li­est pub­lished bac­te­ria pho­tos. Source

Dis­con­tent with com­mu­ni­cat­ing mi­cro­scopic ob­ser­va­tions with hand-drawn il­lus­tra­tions, Koch pi­o­neered the pho­tog­ra­phy of bac­te­ria. On suit­able days, Koch would set up to shoot out­doors. In his 1877 pub­li­ca­tion Koch ex­plains how to take pho­tographs out­side through a ba­sic mi­cro­scope:

"Clean all the lenses, screw them in com­pletely, and place the il­lu­mi­nat­ing mir­ror on the sunny side of the mi­cro­scope. With a dark cloth over your head, look through the ground glass and ad­just the light and fo­cus the spec­i­men… Once the im­age is in fo­cus… go in­side to pre­pare the pho­to­graphic plates. In the darkroom…remove a clean glass plate with for­ceps and pour over its sur­face the iodized col­lo­dion so­lu­tion, mak­ing sure the film spreads evenly and com­pletely. Once the col­lo­dion film is ready, close the dark­room door and care­fully lower the plate into the sil­ver bath… Al­low it to drain and put it in the cas­sette… Go back out­doors to the pho­tomi­cro­graphic ap­pa­ra­tus. Re­move the black cloth…and check to be cer­tain that the proper im­age is still in fo­cus… Then care­fully place the cas­sette, be­ing care­ful not to move any­thing. Af­ter the ex­po­sure… push the slide back in the cas­sette, re­move the cas­sette from the mi­cro­scope, and cover the mi­cro­scope again with the black cloth. This whole pro­ce­dure must be done quickly! Run back to the dark­room with the closed cas­sette, de­velop the plate, and fix the neg­a­tive. If the pho­to­graphic im­age is not com­pletely sharp, or if there are im­per­fec­tions in the emul­sion… it is nec­es­sary to re­peat the whole process, since noth­ing is more dis­heart­en­ing in the pho­to­graphic tech­nique than to try to make prints from un­sat­is­fac­tory neg­a­tives.¹

Fig­ure 1B. A 1982 stamp from Zim­babwe cel­e­brat­ing the cen­ten­nial of Koch's dis­cov­ery of M. tu­ber­cu­lo­sis (DPH per­sonal col­lec­tion).

Quite a process! Fol­low­ing this pro­to­col, Koch re­ports it took at least three hours to ob­tain four to six good pic­tures. Note that this time does not in­clude set­ting up the equip­ment, prepar­ing the bac­te­r­ial sam­ple, or freshly mix­ing the pho­to­graphic chem­i­cals. Yet with skill, pa­tience, and per­se­ver­ance dur­ing his early stud­ies on an­thrax, Koch ob­tained pho­tos of the Gram-pos­i­tive B. an­thracis in a qual­ity that ri­vals im­ages taken to­day. In­deed, as an ex­er­cise of cu­rios­ity, mem­bers of my de­part­ment² took an In­sta­gram pic­ture of B. an­thracis us­ing a cell phone cam­era. The im­age took sec­onds to cap­ture with mod­ern tech­nol­ogy, yet doesn't come close to ri­val­ing Koch's.

Koch's re­al­iza­tion of bac­te­r­ial pho­tog­ra­phy was not merely a pretty pic­ture. The com­mu­ni­ca­tion of ac­cu­rate im­ages of bac­te­r­ial shape was vi­tal to the un­der­stand­ing that mul­ti­ple species of bac­te­ria ex­isted, and Koch's prac­tice in imag­ing rel­a­tively easy-to-cul­ti­vate or­gan­isms like B. an­thracis al­lowed his even­tual rapid suc­cess in dis­cov­er­ing the ex­tremely fas­tid­i­ous M. tu­ber­cu­lo­sis in dis­eased tis­sue. It is this at­ten­tion to de­tail and sci­en­tific re­solve that led Koch to the dis­cov­er­ies that have im­mor­tal­ized him in sci­en­tific, med­ical, and in­deed gen­eral hu­man his­tory (Fig­ure 1B).

Notes:

¹ Brock, Thomas D. (1999) Robert Koch: A Life in Med­i­cine and Bac­te­ri­ol­ogy. ASM Press, p. 61.
² Thanks are given to Katie Mc­Cal­lum for her In­sta­gram ac­count and to Lori Hor­ton, Ma­lik Raynor, and Michelle Swick of the Kohler Lab for the mi­croscopy equip­ment and B. an­thracis sam­ple.