Some Artifacts Encountered in Stained Preparations of Tubercle Bacilli: I. Non-Acid-fast Forms Arising From Mechanical Treatment.

The first report in this series presented evidence to show that artifacts may arise from the mechanical manipulation of tubercle bacilli while they are being spread on a slide for staining (Yegian and Porter, 1944). During such treatment the normally acid-fast cells can be transformed into the minute non-acidfast rods and granules that have been frequently interpreted as immature forms in a reproductive cycle. That the procedure of staining itself may also lead to artifact production in preparations of this organism was suggested by some earlier observations of Yegian and Baisden (1942). They were able to show that spore-resembling structures, referred to as "beads," varied in occurrence with variations in such factors as the chemical composition of the basic fuchsin used for staining, the quantity of NaCl in the dye solution, and the concentration of the dye. The significance of these findings made it seem appropriate for us, while concerned with artifacts in stained preparations of tubercle bacilli, to continue the examination of beads and similar granular forms with the object of establishing, if possible, their real or artifact nature. From the data that have been gathered it appears that Much granules, as well as beads, are products of the staining procedure and are not representative of any pre-existing structure of the tubercle organism.