A study of the nuclear apparatus of bacteria

Dumbbell-shaped bodies giving a positive Feulgen reaction and possessing a strong affinity for nuclear dyes have been observed in resting bacterial spores and vegetative cells from young cultures. A special study was made of the resting and germinating spores of two strains of Bacillus mycoides. Resting spores contain one chromatinic dumbbell body, closely attached to, but distinct from, a rod of non- chromatinic protoplasm. Division forms of this body occur in a few spores. When germination begins, the dumbbell body enters the rod of protoplasm , where it soon becomes invisible. When it reappears at a later stage of the germination process, it has divided into two closely contiguous dumbbell bodies. Further divisions of the chromatinic bodies precede the divisions of the vegetative cells in a regular way. Each vegetative cell usually contains a pair of dumbbell bodies. Similar chromatinic bodies have been demonstrated in the cells of Proteus vulgaris and two Sarcinae. The two single Feulgen-positive bodies described by previous authors in the resting cells of various spore-forming and non-sporing organisms thus appear to consist of two pairs of dumbbell bodies, separated by a delicate boundary. The single ‘cells’ to which these writers refer are in fact short, two-celled filaments. It is concluded that the dumbbell bodies are comparable to the chromosomes of plant and animal cells.