Nucleus and Spindle of Bacillus megatherium in Fission and Sporulation

Abstract

THE cells of Bacillus megatherium have been stained by DeLamater¹, Fitz-James², Robinow³ and others with various dyes to show the chromatin-threads after pretreatment with perchloric acid, chloric acid or other reagents. Chromosomes have been observed occasionally in mitosis as well as a structure which I identify with the spindle described by Lindegren et al. ⁴ in the yeast cell. The large ellipsoidal nucleus containing the chromosomes in the centre of the bacterial cell can be observed in the living cell. This structure is identical with that which DeLamater¹ observed in stained material of Bacillus megatherium and which Whitefield and Murray⁵ observed in stained cells of Shigella dysentriae. The chromosomes appear when dried (unheated) bacterial smears are stained with 1 per cent aqueous gentian violet. They are not clear when stained directly with Giemsa solution but stain clearly with Giemsa after pretreatment with 10 per cent perchloric acid for 20 min. (Fig. 1,a).