352 IMPORTANT VARIETIES OF FISSION-FUNGI. 



m. FAMILY SPIRILLACEAE (MIGULA). SCREW 

 BACTERIA. 



(For family and genus diagnosis, see p. 125.) 



We have adopted the improved definition of genus as 

 originating from LofHer instead of those of Miiller, Cohn, 

 and Ehrenberg for vibrio and spirillum. ^ 



1. Spirals rigid: 



(a) With one (rarely two or three) polar flagellum ; very 

 rarely without flagella. Vibrio. 



(6) With a polar bunch of flagella. Spirillum. 



2. Spirals flexible: Spirochaete. 



Other writers have retained the somewhat older (1889) 

 classification of J. Schroter, which is as follows: 



1 . Cells, bent into more or less pronounced screw forms, 

 rigid, in the vegetative form actively motile, forming en- 

 dogenous spores. Spirillum. 



2. Vegetative cells slightly bent, rigid, usually with 

 half a turn (comma form), actively motile, with arthro- 

 spores-. Microspira. 



This seems to us to have no advantages, but, indeed, 

 great disadvantages, since spores are entirely unknown in 

 most spirilla, arthrospores in microspira are denied by 

 most authors, and, besides, the name microspira has been 

 used by no one for ten years. 



' It certainly does not appear possible to make a sharp separation of 

 the genera vibrio and spirillum according to whether they are pro- 

 vided with one or several polar flagella, and thus there is furnished a 

 new proof of the necessity of great caution in establishing classifica- 

 tions upon the number and arrangement of flagella. According to 

 Giinther, his Vibrio terrigenus has a flagellum on each end, and often 

 bunches of flagella! Kutscher has found some bent forms which pre- 

 sent horny outgrowths, forkings, etc. Since Zettnow (Z. H. xxiv, 

 72) has photographed beautiful bunches of flagella upon the out- 

 growths, one cannot conclude that here involution forms are being 

 dealt with. Severin has made similar observations in the case of his 

 Vibrio denitrificans (C. B. L. iii, 504). Here, however, the formation 

 of branching forms is not under consideration, but triradiate forms 

 (resembling a uterus). Compare the remarks in connection with the 

 actinomyces. 



