Studies upon the life cycles of the bacteria ... / by F. Loḧnis.

  • Felix Löhnis
Date:
1921-
Catalogue details

Licence: Public Domain Mark

Credit: Studies upon the life cycles of the bacteria ... / by F. Loḧnis. Source: Wellcome Collection.

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    lished the second part of his “ Untersuch ungen uber Bacterien” he was of the opinion that the literature even at that time was so voluminous that a complete survey were hardly possible even for the specialist. In 1880 Prazmowslci made a similar remark when he reported on his Unter- suchungen uber die Entwicklungsgeschichte und Fermentwirkung einiger Bakterien.” Since then, every year has added thousands of new bacteriological publications. It would be an inex¬ cusable waste of time to study all of them again in the light of the newly discovered facts. But I earnestly hope that in the discussion of the literature, as presented on the following pages, no important contribution has been overlooked, so that the general situation is presented with fair accuracy, and all those authors have been mentioned who have tried to shed more light upon the life history of the bacteria. Complete reports upon our own experimental investigations will be given later. For making a proper arrangement of this review of the literature, however, our two preliminaiy communi¬ cations, published in 1916, will be used. As will be seen from the following pages, every phase in the life history of the bacteria has been observed by several, sometimes even by many, inde¬ pendent workers, though only in comparatively few cases the complete life cycle of a distinct species has been discovered. It seems best to arrange the whole matter in the following five chapters: I. Different cell forms. II. Reproductive organs. (Gonidia. Regenerative bodies. Spores. Microcysts.) III. Formation of the symplasm and regeneration of cells. IV. Conjunction. V. Methods. In chapters I and II a considerable number of details concerning the different groups of bacteria will have to be discussed. For this purpose, and in accordance with the general standpoint taken at present by most bacteriologists, the following five groups of organisms may be accepted: (a) Cocci. (b) Nonspore-forming rods. (c) Spore-forming rods. (d) Spirilla and spirochaets. (e) Higher bacteria (trichobacteria, mycobacteria). As will be seen later, this arrangement is not in accordance with the true character of and the natural relations existing among the bacteria. But as long as these facts and relations are not more completely known, it will be best to adhere to that more familiar grouping. At the end of Chapters I, II, and III some conclusions will be drawn from the observations reviewed therein, which might be helpful for further investigations. For the same reason the methods have been treated separately in Chapter V. It is hardly necessary to point out that the data collected from the literature are of very different value, and we are often left in doubt as to their correct interpretation. Much of the material discussed on the following pages is awaiting further critical experimental study. Special attention has been given to the morphological side of the subject. Unquestionably the physiological side is of equal or even greater importance. However, as the situation is at present, with most bacteriologists on the one side adhering to the dogma of simplicity and con¬ stancy of the form of the bacteria, while on the other side admitting a more or less considerable variability in their physiological behavior, it appears to be of prominent importance that in the first place a more correct knowledge of the morphological basis of bacteriology will be secured. As soon as the morphology of the different phases in the life cycles of the bacteria will have re¬ ceived adequate treatment, physiological investigations will also furnish much more satisfactory results than are obtainable now. And only after the full life history of the different types of bacteria will have been studied it will become possible to define their natural relations and to come ultimately to a correct systematic arrangement of the various species, genera, and families of the bacteria.
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