NOMENCLATURE AND CLASSIFICATIONS. 165 



In forms like Myxococcus, in which the rods are somewhat scattered, the first 

 preparation for spore-production as seen under the microscope consists in the appear- 

 ance of groups of rods moving with a circular tendency, in which the more central 

 individuals soon become converted into spores. The formation of a cystophore, when 

 it occurs, results from the basal constriction of a papillate mass of rods which pro- 

 jects from the surface of the colony. In the encysted condition there are two classes 

 one in which the individuals thus encysted show little or no modification from the 

 rod-like vegetative state, the other in which they are converted into definite spores. 

 They, however, seem to run into one another. 



The species have been arranged under three genera, as follows : 

 Chondromyces B. & C. 



Rods forming free cysts, in which they remain unmodified. Cysts various, sessile, 

 or borne on a more or less highly developed cystophore. 

 Polyangium Lk. (Myxobacter and Cystobacter syn.). 



Rods forming large, rounded cysts, one or more free within a gelatinous matrix 

 raised above the substratum. 

 Myxococcus Thaxter. 



Rods slender, swarming together after a vegetative period to form definite, more 

 or less encysted, sessile or stalked masses of coccus-like spores. 



That which appears least defensible in Migula's classification is his use of the 

 word Bacterium for the anthrax organism and similar uon-motile bacteria. If this 

 generic name is to be retained, it should be used somewhat as Ehrenberg used it, 

 viz, for motile organisms, and should not be given to entirely different non-motile 

 forms. We have the right to set aside so much of Ehrenberg's description as does 

 not correspond to facts, but not more. We do not know exactly what Ehrenberg 

 had in mind, it is true, but it certainly was not non-motile forms of the type of the 

 anthrax organism. 



Provided one goes back of Cohn's time (1872), which the writer is not disposed 

 to do in case of the bacteria, the one species by which the generic name Bacterium 

 must stand or fall is Bacterium triloculare Ehrenberg. In size and shape, as described 

 and figured, it agrees very well with some of the larger species of Pseudomonas 

 Migula. If we can trust Ehrenberg's distinct statements and his plain figure, it 

 was provided, like most species of Pseudomouas, with one polar flagellum. Ehren- 

 berg also figures and describes it as trilocular or triarticulate. He may have been 

 wrong in including it among his Vibrionides and in figuring and describing it as 

 possessed of a polar flagellum, an organ difficult to make out iu unstained material 

 and with the crude microscopes in use in his day, but, while we bear this in mind, 

 we must not forget that the person who was using these microscopes was no 

 ordinary observer, but a man with remarkable eyesight and with a genius for 

 observations of this kind. Moreover, the tri-locularity which he observed may 

 have been simply the organism iu early stages of division, which is the more likely, 

 since he states that he saw it divide, and because in his specimens from Berlin he 

 sometimes observed four septa and sometimes only two. Ehrenberg's description 

 of the genus Bacterium, taken as a whole, is of course worthless for purposes of 

 modern classification, our ideas of generic values being entirely different from his. 

 A few things only come out of the rubbish heap of this early writing iu a service- 



