Ehrenberg's ciliates one hundred and fifty years later

In 1938 Ehrenberg published a book about the diversity and the structure of microorganisms (animalcula) entitled "Die Infusionsthierchen als vollkommene Organismen" (The Infusoria as complete organisms), considering "Infusoria" as "miniature animals" with eyes. tongue, stomach, tale, horns. trunk, etc. In this work he supported his polygastric theory against the spontaneous generation (in a period of prosperity among biologists) and the position of other researchers, especially from the Naturphilosophie, attributing simplicity to these once considered primitive organisms. Despite of his misinterpretations and that his theory was soon rejected by other workers as Dujardin (1801-1860) or Siebold (1804-1855) and the development of the protoplasm theories, Ehrenberg performed a great work on systematic of free living protists, mainly diatoms. Several genera of ciliates were included within the Polygastrica Class "Enterodela" (animals with intestine) in contraposition of the "Anentera" (animals without intestine-bacteria and algae) and were divided into ten different families. Twenty outstanding plates illustrate descriptions where the precision of the drawings, the meticulous observations and the morphological interpretations can be highlighted. The progress of microscopic techniques and especially the appearance of the electronic microscope have made possible the precise characterization of structures and organelles present in these organisms. structures that in most cases are unequivocally recognized in Ehrenberg drawings. Nowadays, ciliates are on the taxonomic category of Phylum. with time Subclasses grouped into two Subphylums. Ciliates share the following cytological characteristics: presence of two types of nuclei (macro and micronuclei), a cytostome associated to air oral ciliation more or less differentiated. organelles as extrusomes, vacuoles, cytoskeleton, and the presence of cilia and fibrillar elements associated to them as organelles related to the movement and nutrition.