UIHistories Project: A History of the University of Illinois by Kalev Leetaru
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Repository: UIHistories Project: Board of Trustees Minutes - 1882 [PAGE 131]

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125

TBIBE IV. SPIROBACTEBIA.

Cells cylindrical, usually several times as long as wide; curved? or spirally wound; isolated, or united in chains of less or greate r length; with active, spontaneous movements. Genera : Vibrio, Spirillum, Spirochceta. Besides the above, other species, multiplying by self-division, are referred to the following genera: Sarcina, Ascococcus, Streptococcus, Mijconostoc, Cladothrix and Streptothrix. The old genus Monas, formerly including many species of low animals and plants, has been so modified that it now contains only a few forms of doubtful affinities. It must be remembered that these genera are principally based on the shape and association of the cells, and that the latter are supposed to be in their adult condition. It may be that very arbitrary separations are made. It is quite possible, indeed, that the same specific organism assumes, under certain conditions, several of the proposed generic forms; but, it is at least probable that each genus named includes some species which do not change beyond the limits of the description. For instance, the spores of Bacillus would, from appearances alone, be classed as Micrococcus at first, and as Bacterium after a certain period of growth; but Bacterium termo never changes so much that the genus can be mistaken. Billroth goes so far as to claim that all the subjects of Cohn ; s classification, except, perhaps, those constituting the genera Spirillum, and Spirochceta, belong to a single species, which he names Coccobacteria septica, whhVNageli supposes there exists a small number of true species, each of which takes several forms. With such differences of opinion among those most competent to judge, we cannot pronounce with any confidence upon the number or the actual characteristics of the species in existence; but that true species do exist we may feel well assured. When sufficient knowledge has been gained of their life histories, a natural classification can be arranged. In the meantime, such as we have already outlined must continue to be of much service, as it has been in the past. Dr. Luerssen has arranged the following key to the genera:

I. Cells not in [cylindrical] filaments, separating immediately after division, or in couples [or chaplets] free or united in colonies (Zoogloea) by a gelatinous substance. A. Cells dividing in one direction only. a. Cells globular Micrococcus. o. Cells elliptical or shortly cylindrical Bacterium. B. Cells dividing regularly in three directions, thus forming cubical families, having the form of little bags attached side by side, and consisting of 4, 8.16, or more cells ..Sarcina. II. Cells united into cylindrical filaments. A. Filaments straight imperfectly segmented. a. Filaments very fine and short, forming rods Bacillus. b. Filaments very fine and very long Leptothrix. c. Filaments thick and long Beggiatoa. B. Filaments wavy or spiral. a. Filaments short and stiff. a. Filaments slightly wavy, often forming wooly flocks Vibrio. b. Filaments spiral, stiff, moving only forward and backward Spirillum. b. Filaments long, flexible, with rapid undulations, spiral through their whole length, and endowed with great mobility Spirochceta.