Published online by Cambridge University Press: 15 May 2009
Discrete, Feulgen-positive granules, attached to the periphery of bacterial spores, were described by Pietschmann & Rippel (1931), who considered them to be residual cytoplasmic structures; by Stille (1937), who was apparently in doubt as to their nature; and by others, including Robinow (1945), who at first described them as the natural appearance of the spore nucleus. Delaporte (1950) figured the spore nucleus as a less discrete, crescentic body lying against one side of the spore, and in a later study Robinow (1951) accepted this view, and presented evidence to prove that the appearance of the discrete body was an artefact, caused by the hydrolysis with HC1 which was employed in staining. Robinow, in this later study, employed nitric acid instead of hydrochloric acid, and claimed that it gave a truer picture. Both Delaporte and Robinow observed a central, stainable body, which they considered to be cytoplasmic.