The only evidence we have in pathology of living structures in which apparently a differentiation into cell-body and nucleus does not exist, is in the case of bacteria, but then there comes the question whether they may not possess chromatin distributed through their substance, in the form of metachromatic points, as is the case in some infusoria (Trachelocerca, Gruber).
Passing over the earlier authors who regarded this group as allied to Infusoria, a view c ar first contested by Dujardin, T.
C. Williamson (best known as a botanist) in Pritchard's Infusoria, in 1861.
Pritchard's History of the Infusoria (1861); C. T.
Lankester, " On Undulina, the type of a new group of Infusoria," Quart.
He was also a diligent and skilful observer, and busied himself not only with astronomical subjects, such as the double stars, the satellites of Jupiter and the measurement of the polar and equatorial diameters of the sun, but also with biological studies of the circulation of the sap in plants, the fructification of plants, infusoria, &c.
Ehrenberg adds a list of 8 Polygastric Infusoria, 1 fossil infusorian, 5 Phytolitharia and several microscopic fungi.
Ehrenberg), a genus of suctorial Infusoria characterized by the possession of a stalk and cupshaped sheath or theca for the body, and endogenous budding.