472 



THIRD PART. BACTERIA OR SCHIZOMFCETES. 



and these break up into fragments containing from two to several coils and 

 exhibiting active movement; they were formerly known by the name of Ophidomonas, 

 and are said to have a long oscillating cilium at each extremity (Fig. 198 ). 



The same states have been observed in Beggiatoa roseo-persicina as in B. 

 alba ; the net-like zoogloea-form, once known as Clathrocystis, is a peculiar and 

 remarkable feature in this species. 



Cladothrix and Leptothrix buccalis of tooth-caries resemble each other in 



their development. Further details 

 will be found in Zopf s descriptions. 

 The Fungi of mother of vinegar, 

 Arthrobacterium aceti and A. 

 Pastorianum (Hansen), must also 

 be placed in the arthrosporous group. 

 They are distinguished it is true, as 

 Hansen has observed, by the occur- 

 rence of many large vesicular cells 

 between the small cocci or rod-cells 

 of a chain, and the almost constant 

 appearance of these cells at once 

 suggests that they are connected with 

 some process of spore-formation. 

 But the observations afford no distinct 

 support to this view, and the phe- 

 nomenon must for the present be 

 classed with those of involution 

 which were mentioned on a former 

 page. The Micrococcus also of 

 Pasteur's fowl-cholera may also be- 

 long to this group l . 



SECTION CXXXII. The fore- 

 going review of the Bacteria will 

 supply us with some safe means of 

 determining the question of the 

 specific value of observed forms, 

 a question which is at present the 

 subject of much discussion and which 

 must not therefore be ignored in 

 this place. 



There are two views on this subject which appear at least to be diametrically 

 opposed to one another. One of these is, as it seems to me, incorrectly ascribed to 

 Cohn, and maintains that every Bacterium which occurs in the same growth-form 

 and produces the same effects of decomposition, though this latter point does not 

 strictly fall within our limits, represents a species in the sense in which the word 



FIG. 198. Isfggiatoa alba. Curved and spiral forms. A group of 

 attached filaments. R H portions of spiral filaments : C, D, FH in 

 the act of dividing; into smaller fragments and without movement ; // 

 with the separate cells distinctly shown. E swarming fragment 

 ('Spirillum') with a cilium at each end. The sulphur-granules here as in 

 Fig. 197. After Zopf. Magn. 540 times. 



Pasteur in Comptes renclus, 90 (1880), pp. 239, 952, 1030, and 92 (1881), p. 430. 



